Is $7,000 to install a Pioneer dual zone mini split a fair price?

In December, I purchased and had a Pioneer dual zone mini split installed. It was installed incorrectly and has never worked correctly. Over the winter, it constantly threw an error code PC03 (pressure issues). It's been nearly impossible to get the company who installed it out to look at it since February. It's still under warranty, which is why I continue to use this company, although I was told I couldn't switch companies and use the warranty (not sure if this is true). After they recently came out, it seemed OK for a few days, but then threw the same code again once. While operating, it works for a few minutes, stops and goes into standby, then starts again, over and over, without getting the room to the correct temperature. I don't know if this stopping/starting behavior is normal. I feel stuck as I spent $7000 on it only to have it not work correctly, and I don't have enough money to pay another company to come out and diagnose it. I'm looking for any insight. I have been contacting the company at least once a week. In January, I was unfortunately diagnosed with breast cancer and am currently undergoing chemo and other treatments, so my energy level has dropped considerably. I haven't had the energy to continually troubleshoot or go to small claims court, but it's looking like my only option.