I haven't had any seat problems yet. Have you already checked all the connectors, wires, and fuse? How did you rule out that it was the heater element in the seat?
I have the LT3 interior on my 06. I haven't really noticed my back getting too hot. If it gets a little to warm for me I will turn it down to warm instead of hot and I use the heat feature frequently.
If I was gonna change the leather and heating element, I would opt for a whole different kind of seat (Better Quality and Comfort). But it would probably come down to which was the better deal - new better leather and heater vs whole new seat.
