I had heat pump installed in March 2010. Last year in Eastern Washington winter was fairly mild, but right now temp is -8. Auxiliary heat has been running for four hours or more and cannot keep temp at 68. I have a pellet stove and that is helping keep the temp to 68 which is what aux heat is set for now. Can I turn down aux heat and let the pellet stove heat the house. If the system is not running at all will it damage anything? I am concerned about that and my utility bill! Help, my HVAC guy is not returning my calls most likely because he is busy with this freezing weather.

You are experiencing the issues of heat pumps in cold weather. Yes, you can turn it off, use the pellet stove and bundle up!! It's no different than people who shut down a cabin for the winter and turn off the heat pump.