You should be worried.
You should be VERY worried, especially if it's at a Chrysler dealer, the chances of them having any expertise is around 10%.
It's most likely either the locking pump or the SKREEM module, neither one of which is cheap.
The door locks in the XF are operated by air pressure / vacuum supplied by the pump, the SKREEM is the module that works with the key fob to tell the pump to do it's thing.

( You did ask what I thought, right ? )