Reinforcement / Armature visible

The damage is already immense and the expert has put on paper what was already clear. The legal dispute between your construction company and his subcontractor is contractually completely irrelevant between you and the contractor. The construction company can also first fix the damage (they have to do that anyway according to the contract) and can recover the costs from the subcontractor whenever they want (which you don't have to care about).

You can forget about moving in. Legal advice is absolutely necessary if nothing happens now. Also consider that it’s getting colder and in a few weeks there will be ground frost, etc... then digging will become more difficult and no one will want to do it in rain and cold blah blah blah... something needs to happen now. Can’t you get the boss on the line and have a proper conversation with him? Ask him why nothing is happening, etc... if you threaten him with a lawyer, he will just say "go ahead". He holds the stronger position (he has insurance, he knows you face financial ruin, you don’t have legal protection) and you will wait forever. It’s better if the matter is resolved reasonably now. That’s also in both parties' interest. If you go to a lawyer and lawyer’s letters start arriving, it could very well take 2-3 years.

So the plan is as follows:

Our move-in date will be postponed indefinitely. Today I finally received news that the repair work on the foundation will begin tomorrow.

The subcontractor is being uncooperative, so a third company will carry out the job.

I actually prefer this, as the original subcontractor had suggested merely pouring new concrete onto the damaged areas. Even the structural engineer hired by the construction company had to smile about that.

Our neighbors built at the same time with the same company and have exactly the same problem with their foundation.
We have all decided to resolve the problem in a reasonable manner, without prematurely threatening lawyers, to avoid a stalemate and mutual escalation. Nevertheless, we must keep the legal option open.

In a phone call with a partner of the company, I felt I was treated very inappropriately.
Nobody has contacted me until today. I had to inquire about the status by phone and was brushed off with brief, curt words. I was really stunned on the phone...

For now, we will wait for the contractually agreed construction period of 6 months (starting 01.11.2016). Afterwards, I also see more legal chances to achieve something.