My Airtemp split System Heat Pump with remote outdoor unit-air-source was installed in 2014 (gas backup--we live in New England in a Cape Cod style home 2300 sq ft, new energy saving windows, insulated well). It worked fine for many years. We wondered if it needed any routine maintenance and asked the tech, in 2017, whether it needed any service. "if you're replacing the filters at least every three months the gas furnace it doesn't need tuneups. The only outdoor unit needs to be cleaned if it's dirty if not it's just a waste of money and a lot of people don't realize that and some companies take advantage"

We replaced the filters and things were fine. Then in 2021 it began having problems--no cool air during the summer. The tech who installed it came by and said it was a mouse that had chewed some wires (found dead mice nearby). He made a patch repair and said he would come by again. He did not. But it worked, so we left things at that.

This February the heat stopped working. The thermostat was set at 71, but the temp was 67. The auxiliary heat went on. The tech went silent. We tried texting and emailing and finally in March he said he would come by. He came by and found no refrigerant in the unit. He replaced the shredder valves, recharged the system with with 16 lb. of 410 refrigerant. The bill was $995.

But in April, the thermostat was again resting at 67 with the temp set to 71. The outdoor fan was not working. The air was blowing. Our electric bill quadrupled to $850. We have not paid the repair bill yet, because the unit is not repaired. We turned the system off while it's mild outside. And we keep trying to get a hold of this tech but he does not reply promptly. He complained once that "no one wants to work" and it's just him alone.

What would you do in this situation?