If you bring the car to the dealer with this problem, front what I have read, the dealer replaces the entire charging inlet and cable assembly (connects to the battery pack for DC Fast charging and also connects to the on board charger at the front of the car), and if not covered under warranty, this is a very expensive job. Like you suggest, it seems easier to just replace the solenoid if that is really the problem. I am not a car mechanic, but do attempt DIY jobs very frequently. Based on the photos I've seen of the location of the solenoid, it does not look like a job for someone who lacks experience or is not confident of his/her repair skills. Additionally, I have not seen a part number for the solenoid, so I'm not sure how to source just the solenoid. I'm guessing the solenoid manufacturer does not have an interest in selling direct to consumers, so if VW does not offer this part, replacing it becomes a challenge. Keeping it working as long as possible seems to me to be the best and cheapest path to continued successful charging.