I had an air conditioner installed a few years ago and they install went very well and the installer was courteous.
However 10 months later the follow By spring it wasn't working we called and they would not send someone to look and we were told they were very busy with their commercial clients and we said we aren't important because we aren't a large client and we were told yes. No matter what we did they would not honour warranty.
We paid for another service to come and they said when it was installed the line wasn't proper and it leaked coolant they fixed it up and added coolant. They said this does happen and definitely should have been covered.