2011 Buick Enclave CXL 2wd no power after replacing timing chains and crank shaft sensor

Ok, I kept asking and recommending my technician about things to see if he had checked them. He's very stubborn and don't want help when he thinks he knows what he's doing. The day I was going to get the car and take it somewhere else because he had it about a month before starting on it. He told me he was starting on it that day. Three days later he sent me a message saying the chains are in but the car still won't run. First thing I asked him is have you checked the catalytic converters. I never heard back from him so I figured he checked them. After 2 months of him diagnosing it and putting expensive part on it I asked him again. I said "stupid guestion???, Have you checked the catalytic converters? About an hour later he sent me a picture of a convertor and a message that there bad. Well, he put cheap converters on it and it kept setting P0430 & P0420 codes. So I went and got the car. I had name brand converters and 02 sensors put on it. The codes went away. A 100 or so miles down the road it set a P2099 code. I had a muffler shop put the 02 sensors and the Converters on. The code came right back. I've cleaned and checked everything everyone has told me to clean or check. I'm worried the car will ruin my 02 sensors or catalytic converters. Anyone have any comments or ideas for me to do. I broke down and asked a dealership how much for them to take one hour labor to diagnose it. They said $80 and it will be next week before they can do it. I'm not sure but it may be either the best or worse $80 I've spent on it.