I am going to be doing exactly this on my new (to me) MY11 T5.2 Multivan. The OEM kit you need is called the 9W7 with part number 7P6 035 730 - the letters denote the version, with later letters being better, adding A2DP bluetooth audio control support etc. Check eBay they are all over the place, or carsystems.pl from Poland, also JKU sells them from here in Australia with warranty.
I am starting a thread with pictures etc. once I get it all done over in the Transporter subforum.
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