Lasted a year and now heats to infinity until I unplug it

I bought two of these a year ago and used them for about 1/3rd of the winter days in Portland, OR (where it doesn't get that cold). They worked great for the first two months. They never got too hot to the touch and were good about keeping the temperature within 0 to +2 degrees from my digital set temperature. They are easy to roll from place to place and are also nice and quiet. After the first two months the first unit began experiencing "the problem"...It would reach its set temperature and then just keep on going. When it hit 95 degrees in my daughter's room at 3am, I knew I had a serious problem. I tried it on the medium power setting and it seemed to work just fine...for another month until that setting also began to experience "the problem"...Fast forward to the beginning of this heating season (11 months since I bought the units) and now the second heater is having the same un-moderated, overheating problem that the first one did. I'm now searching for company recalls and should probably follow up by submitting some sort of official report since they clearly represent a fire hazard, especially if you aren't in the room to notice that its getting as hot as Dante's Inferno in there.