The cantilever staircase does not hold, the stair builder is not a staircase builder

You do have rights (for example, the Building Code regulates such a case). You just have to enforce them in court if necessary. I have already told you how to do that.

Therefore, in my opinion, you have a right of withdrawal from the contract and a claim for damages.

If you have the time, exactly. I suspect the contractor will not want to pay voluntarily or, worse, will not be able to.

That sounds so simple. But it probably won't be that simple.

Personally, I also got involved in a "botch" (not a cheap purchase). The case has been going on for 10 months, the perpetrator has nothing and will never have anything. Lawyers argue sluggishly. Every time, I push myself to make a timely decision; the opposing party repeatedly misses deadlines or doesn't respond at all. Nothing but expenses so far. Now we are demanding our money back (for that you could get at least 10 stairs) and I bet we will have to sue for it.

There are also some formulations in the Building Code. For example, I remember that years ago, there was a warning about so-called fake shops that advertise goods below average value. That applies here, too. Someone who offers orders in classified ads probably won't reach customers otherwise. One should think with common sense. The price is the mirror of quality.
How much money are we talking about?

One also has to admit that if one was naive, one can't necessarily demand the right but has to pay the tuition fee.
Ultimately, a shame about the botched wall!

I lack the belief that an incompetent craftsman would voluntarily be reasonable. So yes, to a lawyer. But don’t wait for the repayment, instead immediately reassign the staircase once the lawyer has said "from now on." Climbing through the house with ladders or the construction staircase for possibly a whole appeal process? No thanks. The scope of possibilities is narrowly limited: that the craftsman would be ordered to pay the additional costs of replacement performance by a professional, never ever. I see the TE either substantially financing further or settling for a simple staircase. Like the fisherman's Ilsebill. Sometimes even a shot misses backwards.

Hello everyone,
the craftsman initially fastened the steps with concrete anchors, but they more or less immediately pulled out of the wall under load. In the second attempt, the craftsman removed the concrete anchors and glued threaded rods with an adhesive from Hilti. Now one threaded rod is pulling out of the wall again on one step, see photo. We have a 20 cm reinforced concrete wall and the current threaded rods are 15 cm long.

In my opinion (I’m an amateur, don’t scold me) the bearing surface and thus the point load are too high. What do you think? Should it have held even with proper execution?

Currently, we are considering increasing the bearing surface with a plate welded to the current steps and additional glued threaded rods, see sample photo.

Thanks and regards

How do you see that?

Not only you, but also the craftsman is an amateur. Nothing should come out of clean (!) drill holes.

I don’t trust him anymore. Should I hire a lawyer and demand my money back or give him another chance? I’m afraid we might break something if the staircase wasn’t properly calculated and fixed.

Hire a lawyer only if you have absolutely no idea about contracts. I would try to settle it myself first – demand the money back and compensation for any damages as a starting point.

Pictures of the whole thing would be interesting. Normally, everything can be fixed firmly to a concrete wall.

This staircase design has an unusual leverage effect on the stops, combined with a dynamically tolerable load and a high risk of injury in case of failure. You are right with your statement – but I wouldn’t let laymen handle it.

I can’t imagine that the OP will find someone who will fix the botch job. The right solution is to reassign it. To a specialist company and claim the additional costs as damages.

I see it the same way. The damages claim is a kind of "bargaining chip." Getting that paid is unlikely.

You just have to admit that if you were naive, you don’t necessarily have the right to claim but have to pay your learning fees. Ultimately, a pity about the botched wall!

That is a possible outcome – I don’t see it that far yet.

I don’t believe an incompetent craftsman would voluntarily admit fault. So yes, lawyer.

See above: A lawyer costs time and money and only increases the chances of a good result if you yourself have no knowledge of contract law and negotiation.

Currently we are considering enlarging the bearing surface with a sheet metal welded to the current steps with additional glued threaded rods, see example photo.

Sounds to me like you would be following one misjudgment immediately with a second one.

So you wanted the steps like that? But no architect planned that. How is the railing supposed to be attached there?