I have had the same experience, dealers deny any problem, prevarication over testing and failure to deliver.We bought the van from VW Liverpool but they were not very helpful when the roof leaked so eventually we took it to VW Van Centre Llandudno Junction. They have sorted it although, I am not sure how far we would have got if Adrain from VWEO hadn’t been on the case. It seems as though that was the best way to keep things moving to a hopefully successful conclusion. To be fair, once everyone was on the same page Llandudno were excellent at communicating and doing what they said they would. The biggest problem was the need for three booked visits, once to show them the issue, once for them to follow the official “does it leak” VW test and once to actually get it fixed.
I did also speak with Hereford and Birmingham dealers in November but both said they had no knowledge of a bellows problem!
Progress is only made by engaging VWEO.