Hoptpoint TDC62 Ultima thermostats keep going - ?

Lost heat so replaced the thermostats in the back. But the new ones seem to have gone already ( within 2 days) . What did seem odd though was once it started working again and I did notice that the heat in the drum seemed a lot hotter than normal. Suspect that this high heat is causing the thermostats to go so any ideas what is causing it.
The condenser is clear and kept clean. The door filter is also clear. Notice that cold air comes from front vent and hot seems to be at back of unit. Pretty sure that I should have warm air coming out of the from vent.