We endured two years of grief with electric door on SusiBus T5. I won't go into all the details but we did learn a few things along this painful journey.
1. Not to order one for SusiBus T6.
2. More important to owners currently suffering the dreaded door hokey Cokey.
THERE A FIX ! A VW FIX THAT WORKS!
You don't need replacement rollers, or runners, or handles,
It's a SOFTWARE FIX that VW know about, but for a reason known only to themselves, they seem to have failed to distribute the information amongst thier workshops.
I have previously posted the code number for the software update but I'm sorry I haven't be able to track it down, it was posted probably late 2013/14.
I got the information from a fellow Cali owner at the first Brean meeting, who suggested the I contacted the service manager at Cordwallis VW Van Centre Heathrow, so perhaps a phone call to them might furnish you with the details. I don't know how they will take it if he's suddenly in inundated with a load of people requesting information, but I feel VW have failed badly not distributing this information amongst their dealers.
3. In the meantime stop the door damaging the wheel arch put a little bit of sticky backed foam just on the inside of the door where it catches a wheel arch.