I sourced a standard three pin plug kitchen plinth heater off ebay, which I cleaned up and fitted and was working absolutely fine, for about a year. Just to take the chill off the air first thing in the mornings. Now, it's stopped kicking out hot air, and is barely doing more than circulating lukewarm at best. Question is, is the built in thermostat DIY obtainable/serviceable/replaceable or shall I just ditch it and get another?