I have had the same issue with my van since new. It was totally standard from VW and the wheel was always slightly to the right and pulled to the left when let go.
Took it back to VW 3 times, who charge me of course, and they just kept trying to align it but the problem was never fixed.
Around 6 months later I put some KW V3+ coilovers on it and set it about 70mm lower than standard, it then went to VW for alignment. Same again, steering wheel to the right and pulled to the left when released.
What was interesting was that a couple months later I realised the van was too low for towing my car trailer so I raised it up about 20mm. Without alignment the van drove perfectly but I was worried the tyres might be scrubbing so took it back to VW for alignment. It came back out with the original issue again.
I drove it for a year like this which was annoying so eventually I thought I would spend the money and take it to a proper company who just specialise in alignment called String Theory in Stratford Upon Avon.
I haven't posted about this yet as I was hoping they would fix it and wanted to give them the opportunity to rectify, however after a couple of trips and around £500 it is worse than it was and now they do not reply to me.
First trip there they completely messed it up. They were really good about it though and just put it down to a mistake on one of the technicians.
The second time the owner did it and it was better but told me it might settle and improve. I was away for a few months with work so couldn't put any mileage on the van but after 6 months it is still the same. Wheel to the right and pulls to the left when let go.
I contacted them but just got ignored so I am guessing they can't be bothered to fix it.
So several 100's of pounds out of pocket and a few years later I still have the same issue.
My conclusion is that one of the steering arms is longer than the other on the T6 and that the bushes are super soft, so depending on how well the van is settled before making adjustments, has a huge affect and with one steering arm being longer than the other, the geometry is effected differently through the suspension travel. This was apparent when raising the van 20mm fixed the issue and on especially warm days the problem is worse for me as presumably the bushes flex more.
My conclusion is that to fix this I need to fit some polybushes and go from there. Are there any on the market?
Mat