C5 A6 has no heat - A/C and all other functions such as fan, heated seats working fine. VAGCOM show faulty Control Module for Climatronic system.

Found a number of units on eBay. My control unit part number is:

4BO 820 043AD

I have found the following with the same functions - heated seats, etc. but the part numbers are not exact, for example:

4BO 820 043AR - 2004 unit
4BO 820 043Q - 2001 unit

Anyone know if the difference in the final couple of letters in the part number is a non-issue?

Thanks!