We have a body shop but it will be very hard to give meaningful technical advice without seeing the car. Sounds like you really need legal advice.
Two pieces of info I can offer. First is that its probably harder to repair an improperly repaired car than to fix the original damage. Gap distances are the result of poorly set-up inner structure usually. Second, all cars that have been in major accidents are worth much less than otherwise. I have seen owners try to recover this value from the insurance company and it doesn't work because the only way to establish current value is to sell it.
My guess is that you will not be satisfied with the further repairs. I would seek legal advice on how to deal with the second part of my info.
Bosch Master, ASE Master, L1
33 years MB technician