I'll copy what I put on the Facebook post - 'Ah just seen this, I am the seller 👍
The rust bubble is superficial, only on one side and is completely solid underneath. Doesn't seem like it will cost much to fix. Appreciate absolutely no one is going to believe that online, but I welcome anyone to come and view the car who may be interested at the 5k mark.
But tbh, It seems I may be best keeping hold of it, sacking off buying an UP GTI and doing the small remediation work - and continuing my quiet enjoyment of it. Selling cars on eBay/Facebook is an absolute nightmare'