Wall Thermostat

Has anyone encountered problems with their Wall mounted thermostat when trying to run the furnace? Mine seems to blow the fuse in the thermostat on a regular basis. In the last 30 days I have gone through at least 6 or more of the internal glass tube style fuse in the thermostat. So far I have not been able to get the temperature in the unit over 62 degrees on a cold day or night.
I had a local (to the area we were camping) service tech come out. He bypassed the thermostat and proved the furnace runs fine and will bake a person right out of the unit, but as soon as you go bak to the thermostat being in control, pop goes the fuse once we get right around or slightly above 62 degrees..