Sorry to hear the issue is still present. I would be more than happy to help you out, and ensure everything is working properly. Since you have, already, tried resetting the device, could you try following some of these steps below to see if that helps?
- Air vents that direct warm air across the thermostat
- Electrical outlets
- Appliances - including large televisions
- Plumbing (hot water pipes in old buildings are frequently uninsulated!)
- Other potential heat sources
- Warm air in the wall behind the thermostat
Please let me know if any of that helps isolate the issue.