My fuel flap refused to open, and I managed to force it open with a plastic trim tool. The actuator had failed, so I purchased a new on from TPs at £30. Looked easy to fit, as several videos on YouTube. Unfortunately, Skoda has made it difficult to remove the fuel door, as it is necessary now to remove the o/s rear wheel, the wheel liner to locate the nuts/screw, which hold it on. Then you can pull away the whole assembly from the tank nozzle and replace the actuator. I took it to my local mechanical garage , and they fixed it for £40.
If you force the fuel flap open, you may break of a piece of the plastic slot the actuator arm fin rotates into when locked. I did, but it still locks. It may be possible to slightly pull open the flap, push a slim tool into the slot and rotate the horizontal fin vertical.