Anti theft mode

Hi , I had got into a accident with my car and needed the axle repaired . I sent it into Canadian tire to get it fixed and while it was in there. They told me they tinkered with the anti theft to by pass it to start the vehicle . I also have a car with a loan company that has GPS and is able to shut the car off if I do not make my payments. the car was turned on for 24 hours while I got it fixed at Canadian tire and worked fine when I drove it home. my car company had shut it off again for 2 days and they turned it back on. Thursday , said everything was good on there side it was enabled and should start.I tried to start it and the anti theft light was coming on and my lights and everything work but it won’t crank. I tried all the things online like removing the battery and leaving it which is what Canadian tire said they did and nothing still.eventually my battery was getting low and shutting off. so I tried boosting it and still nothing. I took it into Bretts dealership now they are telling me I need a whole new fuse block and it’s going to cost me $600.00. I don’t know much about vehicle but this doesn’t seem right to me. thanks