Go buy a damn grill and put it on yourself. Letting that shop near the car again would be rather stupid.
It's four screws, as James has pointed out. I'd bet they backed into the car with another car - there is no way they took grill off -that is a cover story.

As to the TPMS, prepare to spend a LOT of money and STILL not get the TPMS working. You have ONE chance to get that working, and it starts with YOU reading the attachements and understanding what is required - because most tire shops make invalid assumptions. If you think you are going to take it to a tire shop and they are going to 'fix it', know your chances are 1 in about 500. IF you understand the system, your chances rise to 1 in maybe 5; again, these tire shops make invalid assumptions.

Sorry, on this computer I can't read these documents. They may be the same document. Clint is a retired Chrysler engineer that worked on the TPMS, airbag and seatbelt systems in the Crossfire. If someone tells you he is wrong, walk away.