begin a documented period of time getting your information together and for presentation to a lawyer. I would not accept this answer as Post Tension or Cable Lok process is to prevent just this from happening. You need to get the contracts, take pictures, get phone calls documented with dates and names. Send in a letter of formal complaint to the company from your consel and then see what happens.
In my region, we refer to this process as cable lok. The process in my region is to install steel cables on both north south and east west sides of the foundation that cross each other and after curing the cables are tightened down and pull the concrete slab together and prevent all cracks. If a crack does appear, then a tweaking of the high tension cables can pull that back into place. Its almost like spokes on a bike rim.
You are not being delt with in a professional manner and you need to let them know that you will not accept this lame excuse.
Do a good prep job and send that demand letter in with a lawyers paper and signature and I am sure you will see results. It should also be under warranty, ours in my region are for a life time and even transferrable.