AUdi A6 gas tank button

There is no button to open the gas door from the inside of the car.  As long as the doors are unlocked, you should be able to push in the far right side of the gas door and the left side will pop open. I too spent hours looking for this non existent button..I went as far as to going back to the car dealership.

The unlock button unlocks the doors and tank

Button to open the gas tank is pushed all the way and gas tank won't open.

Should be somewhere on/near the driver's side door.