Business ProfileforSt Johnsbury Buick GMC

I took my 2016 cadillac ats to ******** on 7-5-22 for a random misfire issue.-I recieved a call from ********. They had been driving for 1 hour and had found no issues. I needed to approve more time diagnosing. I allowed them to continue trying to find the issue with my car -8:54AM 7-6-22 ******* at ********* called and said my engine failed and would need to be completely replaced. ******* described the damage to the engine as scored piston walls and possibly a cracked piston. This was after mechanics had tried to diagnose the issue for 1 hour and found zero issues.So I approved replacing the entire engine with a used ****** mile engine.5 weeks later ,August 9, i recieved my car back. It still had the same misfire issue ******** now deny doing any diagnosis on the engine that was replaced. It was replaced without knowing what the issue was.They have no record of any damage to the engine that was replaced and have no record of me approving that replacement.I was mislead with a list of damages to approve a costly engine replacement. Now there is no records of any damages or record of approval to justify the replacement. I would not have approved an engine replacement without even knowing the issue! they refuse to refund my $6,154.42 and say that I approved the engine replacement without diagnosis. They can not give me any documentation to justify engine replacement or what I may have agreed to.