You can buy Webasto thermotopC reconditioned and new from places that supply campervan and yachts but they will lack the setup of the Audi thermotopZ so won’t integrate properly with the car’s systems and are very expensive.
Getting your existing thermotop serviced by the above groups is probably a decent option but, again, pricy.
I just replaced mine with a second hand one. I’ve bought my webastos from the forum - Steve and Sarge.
2/2 working fine.
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