Aire One Heating & Cooling Kw

Had a Carrier Ductless 24,000 Btu seer heatpump installed - 900sq ft home. 2 x 9000 btu wall units installed downstairs. 1 x 12,000 btu unit installed in mainroom upstairs.
Downstairs is fine. Warm as per the temp on the hand sets.
Upstairs is always cold unless it is way above freezing out. Example. This morning it was 4c outside. Handset set for 20c and it was at 8am 17c in the room. I can turn up the handset to 24c but the temp after 4 hrs is only at 18c. This has been going on since the fall when i first started using in the heat mode. (It also didnt keep the room cool in the summer and humidity went to 86%).
I was also sold a $450.00 ecobee thermostat as i wanted to be able to control the system while i am away. I have had 3 service calls. 1st one said he didn't know anything about the ducted heatpumps - and after a short discussion outside with someone with the company, said he was leaving and would have some else come. No one followed up. 2nd guy came and tried to tell me that thermostats are not very accurate, and that no way the system can be controlled using the ecobee. Said he would followup on a wifi solution. Was called 3 days later from aireone and was told it would cost $500. But couldnt say how it worked. 3rd guy came in jan from aireone kw to alter flame on gas fire place super guy - did the work. - i asked him if he knew much about heat pumps - he fiddled around with handset. Also confirmed that not likely ecobee would not work with the system. Said he would consult with someone at office and have them call me. Its now march. No followup. No one actually has looked at the system. Its still cold upstairs in my house. I am a single female pensioner - who is spoken to like i cant tell its cold in here because the $450 thermostat might not be accurate - despite me showing him the 3 other thermostats i had bought to confirm the temp in here. Isnt there someone who owns this company - interested in ensuring that there is accountability for what they installed is actually working and if it isnt- fixes the problem??
Summary:
1. Upstairs heat pump is not maintaining temp on handset while downstairs heatpumps do. Obviously the outside heatpump is working - is the upstairs wall unit defective???
2. Why was sold a $450 thermostat that doesnt control the system. It only can tell me temperature presently in the room and the temperature outside.

I have had 3 separate service guys come out.