need advice...getting jerked around by home warranty co.

[scotchnrocks]

I mortgaged a new condo in October 2006. Since then, I've placed a call for the 4th time now to have my A/C looked at. Each time they come out they charge the freon and say it is fixed. The A/C and heat then work for a few days and then stop (fan keeps blowing but the air is the same temperature as the room temperature, no matter if it's on heat or cold). Obviously there is a leak somewhere in the system that they do not want to find/repair, probably until my new home warranty is up. How do I need to handle this so that I don't get the shaft when my warranty is up a few months from now?