I have had 7 mechanics look at this issue and no one can fix it!!!!

I have Raynaud's and cold weather makes it so I can barely move my hands and can be in danger of loosing my fingers.

Sub-zero temps in Buffalo today. :-( The heater works as long as the car is moving. When stopped or idling the heater blows cold air! Had it checked last winter, they told me they could not find a leak, said it probably was leaking into the engine, would cost $2000.00 to fix a broken gasket. Temperature gauge works fine, car is not overheating. I add about a cup of anti-freeze every 2 weeks. Please help!