Came out to call for a thermostat issue. Customer stated that she had to turn the thermostat 5-6 degrees higher than normal, and has had to do that for the past few weeks. I checked temperature inside the home and it was 74. Thermostat was reading 77 in the home. After discussing with customer about the thermostat issue and the temperature difference, I went ahead and changed out the thermostat we installed a couple of years ago under warranty with a Honeywell T6. Showed customer how to use new thermostat. Checked furnace operations and had no issues. Did not charge customer due to customer not pleased with thermostat we installed.