Heat / furnace Issue

[Lauren]

The heating system in our 32TK3 is sporatic. Sometimes it comes on; sometimes not. Have replaced the thermostat. When we go to bed at night we can wake up and it is cold; furnace has not kicked on. Sometimes it can come on a few times and then it won't. If you turn the thermostat off on the bottom and back on the furnace kicks on! It is still warranty but am looking for any input anyone might have. Was to take it to a dealer next week for all the warranty issues but they called and told me they would not do the work as I did not buy it from them (there was a good reason I did not). (Won't get into that in this message, but will - at some point - in another one. There is at least one real bad dealer out there). Comments on the heat thing welcome. Thanks.