I am trying to install myself a digital thermsotat Hunter Auto Saver 550 but the wires from the wall don't match the new unit. Any ideas?

Sure. You will have to trace the wires from the wall down to the furnace and see how it is wired up at the furnace and see what colors they used for what item. Then just transpose those colored wires to the new stat.

A funny thing happened when I finally called the Hunter Help Deck at the toll free number I got from their website... my call was answered very quickly and the man politely asked me what letters on my thermostat had wires running to them. When I opened the cover and listed them off to him, he immediately informed me I had purchased the incorrect model for my heat pump and he told me the correct model number that I would need. I went to store where I had purchased the unit several months earlier and explained my dilemma. With neither package nor receipt, they issued a store credit, per policy for these unique circumstances. I then went inside and bought the right one, went home and installed it. I don't know if this is the appropriate forum to mention the hardware store's name where this all took place, but it rhymes with FLOWES... Thank you very much