Maybe instead of cleaning the coils they are replacing them now once or twice a year? The thermostat too just to make sure it's accurate. Yikes!
I will tell you when I purchased my home the existing thermostat was reading a couple of degrees higher and I did have to change it myself. So that's possible. Mold on the coils or in the airhandler is not an unusual problem. Over time you will get some and it just needs to be cleaned. As for the capacitor change out, although the part is cheap on Amazon, the company is charging you for the truck roll and technicians time which will vary. Unfortunately, when the capacitor goes bad it's usually hot, you want A/C and you will pay anything to get it back. If you are very handy you can buy a spare capacitor on Amazon and have it on hand because over time it will go bad.
The Carrier systems installed in the Villages are very good and have an excellent warrenty. Just get a reliable company to service it and it should last about 15-20 years on average.