If the heating element is a separate "pad" then just replace the pad, and refit the original leather cover.
If the heating element is integrated into the leather cover, then you have two choices:
1. Replace with a new leather cover (with integrated heating element).
2. Keep the existing cover, but insert a separate "pad" beneath it.
I had the cover replaced under warranty so I'm not sure of how easy/difficult it is. There are some part numbers in the thread.
Does anyone have access to EPC who can punch in Gary's VIN and check if he has integrated element or not?