Otto's BMW

My car was in Otto's BMW service for a battery wire change. The air conditioner was working before the service, but after the service, when I turned on the AC for the first time as the weather got hot, the AC did not turn on. I'm wondering if the dealer did anything to damage the AC. They need to check the car and confirm that no original parts have been replaced and that the work on the battery cable was done correctly. Otto BMW rejected to review the work they did (*** - service manager). I demand that they check the car and see if their workers did something wrong on purpose or by mistake. The battery cable was rusty, and a few years ago, they told us about that. The dealer has to explain how the cable can rust. Why do other dealers say that it cannot happen? Was it ever replaced on the car? Otto BMW wanted to charge us $4000 for the seat front replacement as the belt did not work. This is in their files. I checked the seat and found a pin size of a paper jam. I removed it with a toothpick. It was a 10-second job.