You probably paid extra for it and if it's under warranty, take it in and don't take no for an answer until it's fixed.
This was on the Car Talk guys a couple of weeks ago. Your problem may be different than the one this lady was experiencing.
Every time her husband drove the car the heated seat would come on. After asking her a few questions it was determined that he was a rather large man and when he sat in the seat, it grounded out the contacts and made the warmer come on.
If it's out of warranty, you could always just unhook the connection but that would mean you'd have to do without a seat warmer. That would be the simplest and cheapest method.
