[CNC]

Really poor design from VW and they don't do this on a sunroof service, so really its up to you.

Not entirely VW's fault as they didn't design the panoramic roof (although they did choose to fit the design), it's made by a company called Inteva Panoramic Offerings

 

[CNC]

They must be aware that the design is not fit for purpose and could have helped customers fix, but refuse the acknowledge it so AFAIC, its VWs fault.

It is your opinion the design is not fit for purpose, and I'm sure all other owners who have had the drain tube blockage problem would agree with you, but the majority of owners have not had sunroof problems so as far as VW are concerned it is fit for purpose.

That's not to say the drain tubes don't require maintenance, and to be on the safe side it would seem to be preferable to clean them despite this not being a noted requirement by VW.

I covered 148k miles in my Tiguan without any sunroof problems at all as have many other owners.

I do sympathise with owners who have had water ingress in the car with the subsequent hassle of getting it sorted out, not a nice position to find yourself in.