Hi I needed a mirror earlier this year, long story but the company below sorted me details below. found the info via this forum thread below
I too have a T6 Highline. 2016 model.
The o/s mirror was knocked off by an over enthusiastic delivery driver a few weeks before Christmas.
Looked at assorted replacement options.
Decided against the non OEM options having read very mixed reviews.
Replacement at local VW dealer was a non starter. Eye wateringly expensive.
In the end I went with 2x genuine T6.1 Startline mirrors (O/S & N/S). This means that they don't need painting.
Purchased for £70 each from Exploria Ltd on eBay.
www.exploria-online.co.uk
They are a conversion company and had taken them off a brand new vehicle.
I have checked and they still have availability.
Genuine VW Transporter T6 T6.1 O/S Wing Mirror | eBay
Fiddly to do but not difficult. No wires to cut. Plug and play.
Make sure that you buy some replacement door card fastener clips as they break easily.
I also found that a set of plastic trim removal tools made life easier.