Climate control panel with heated seat function (help with part numbers please)

[Teza511]

Hi how do i find out what part number i need to upgrade my a/c unit to the one with heated seat function ? I think the 8E0 820 043 Part is right but what letters do i need it to have on the end ?
I have a Audi A4 B7 Avant 2007. I have the harnes from kufatec.

 

[solaris]

I wouldn't buy it new, get in touch with the scrappers or eBay..think there is one here but i'm sure if you keep looking a cheaper on will pop up.