Problems with the plumber - what about warranty

Hello,
We are having problems with the plumber. Among other things, he forgot to install parts and the wall had to be reopened three times in the finished tiled new building. This is just one of several points.
We have been living in the house since 01.06.20 and not all defects have been fixed yet. Therefore, we set two deadlines. The first deadline expired on 12.08.20. The plumber contacted us on 11.08.20 and informed us that the required spare parts were available and that he would contact us again tomorrow (12.08). However, this did not happen. Therefore, we set an additional deadline until today. Now he contacts us today and informs us that not all spare parts are available yet. The earliest he can come is the end of this week. Since moving in, there have already been about 4 attempts to repair all defects. So far without success. We have only paid a partial payment of about 50 percent and have not yet received any further invoice. We are also still waiting for all documents as well as the completed applications for the BAFA subsidy.

How would you proceed? We informed him when setting the deadlines that we would commission another company if he did not meet the deadline. We would now prefer to do so.

BUT: One has to somehow deal with the company, right? What about warranty claims against the original company?
Due to the many errors, we have a bad feeling about all his trades. However, I assume that all the in-wall installations will probably hold. I am worried about the heating system, which can of course have malfunctions from time to time. Does the plumber have to come out and bear the costs, or will any malfunction after commissioning anyway be handled by the heating manufacturer (ELCO)? Otherwise, the plumber would probably just leave me out in the cold at first.

I also suspect that the plumber will simply add the additional costs to his invoice if we now commission someone else. Originally, we were given a fixed price in the offer. The only works that were done additionally are the installation of the WCs, WC flush buttons, and the two showers. But these very items are still defective among other things. He carried out the work but never quoted a price for these works. So far, only the fixed price offer (without installation) for the fittings is available as a basis.

Entrepreneurs always have the right to remedy defects/performance after the fact. My lawyer recommended a period of 10-14 days regarding a deadline. However, due to Corona, I can understand that deliveries of needed parts or devices can be significantly delayed, which is why I would currently allow more time. Regarding the heating system, you need to find out what contract your installer has with the manufacturer. For me, for example, only the factory service always comes when something is wrong.

Entrepreneurs always have the right to remedy defects/supplementary performance. My lawyer recommended a period of 10-14 days regarding a deadline. However, due to Corona, I can understand that deliveries of needed parts or devices can be severely delayed, which is why I would currently grant more time. Regarding the heating system, you need to find out what kind of contract your installer has with the manufacturer. For example, in my case, only the factory service comes if there are any issues.

We initially gave the plumber a deadline of 2 weeks to which he basically did not respond. Then a grace period of just under a week. I spoke about this with a lawyer friend who also recommended it to me that way. We discussed the spare parts with the plumber at the last appointment. That appointment was already 4-5 weeks ago. To speed up the whole thing, at the first 2 attempts to rectify, I initially requested replacement parts directly from Grohe as a goodwill gesture and also received them within 2 days. But the 3rd time I would not have gotten anything anymore and asked the plumber to order it himself. He just told me that he gets them through the wholesaler and that nothing was currently available there. So we have been waiting for weeks again.

that is the typical dilemma that the guys have too much to do and just keep moving on. Does the shoe hurt immensely? Like nothing can be used at all?

Have you all paid to have a means of pressure here just in case?

this is the typical dilemma that the guys have too much to do and just keep moving on. Is the problem really that bad? So that nothing at all can be used?

Have you all paid to have a pressure tool here just in case?

We have been using only the guest bathroom for 10 weeks. The shower upstairs is slightly defective. You could shower but we have refrained so far because the plumber already started claiming last time that it was our fault!
We have only paid 50 percent so far. I spoke to another plumber this morning. Of course, they don’t want to finish what others started because of the warranty. The plumber seems to barely care about the money. We have already been living in the house for 10 weeks and the final bill is not here yet. Of course, it’s not finished yet.
He wants to come by on Friday or Monday now. We have not confirmed that yet. He just sent me a short WhatsApp message yesterday.
Our problem is that we actually don’t want to have him here anymore. He obviously lies and the work is also poor. Example: Last week the spare parts were supposed to have arrived. This week they suddenly are no longer there, so he can’t keep the deadline.

A short list of some mistakes that come to mind quickly:
- Screed drying program set incorrectly (only at 30 degrees)
- Flush throttle in the toilet not installed
- Concealed fitting forgotten to be installed
- Heating sensor tightened too tightly (which caused water leakage that was not reported and heating malfunction)
- Wrong heating system delivered (although it’s an upgrade with no extra cost for us, but much bigger as well). Planned space in the utility room is gone.
- Pipes planned incorrectly. We had a niche intended for the previous smaller heater. The pipes run along the back wall of the niche. Idea from the plumber. We thought it was fine, of course. When the heater arrived he said that the heater cannot go in front of the pipes. So the niche is useless. Again, space lost.
- Seal around the shower forgotten. No silicone or anything was applied. This almost caused water damage due to the next point
- Grohe shower fitting was damaged TWICE during installation!
- Missing concealed fitting was installed crooked during rework. The wall had to be opened again
- etc. etc.

Are you building with the [GU] or did you hire the plumber yourself? If [GU], I would inform him immediately. Our [GU] would immediately seek conversation with him and possibly send a more reliable plumber. If direct: dilemma