I'll have my Hoe for a good long time and got my stuff at The Seat Shop a couple of years ago -- new OE style bottom cover, seat cushion, and heater pad. If you don't use the seat heater you could get by without a new pad, but getting the old one off (and assuming it's in good enough condition to last, and it survives the removal) will be a hassle.
Pics of my work here:
What menus on the tech2 gets you there? My roof vents blow out hot. I have these notes... HVAC recalibration is found under the "Body" menus. HVAC Recalibration – Body > Heating and Air Conditioning > Special Functions > Miscellaneous Test HVAC Recalibration – Body > Heating and Air...
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You can get by with less expensive parts if that's the way you want to go. Others will have some less expensive suggestions.