Fule door

The release on most of them is just the door locks. There's a pin that engages

The release on most of them is just the door locks. There's a pin that engages with the locks via a pneumatic pump that actuates all the other door locks. By unlocking the car, it should be free to open

If the locking pin is stuck or the vacuum system is faulty, you may have to use a little flat screwdriver to carefully pick it open.

My 2001 Golf has a release just for the fuel door on the driver's door, located a little below the door handle. There is a small icon on it. It needs to be pulled up slightly and the fuel door will unlatch.