It does hold GDPR data, I posted pictures of the inside of my home and also described details of my location. And as you said, it has my email etc. If Virgin Media want to rely on public forums so they don't have to spend money on actually providing direct support for their paying customers, fine. But it does not give them a licence to ignore my rights when it comes to GDPR and the right to erasure. There is very little option to get help/support directly with Virgin Media, it's all designed to prevent paying users from getting phone or email support. Now that my request for help is not needed anymore, I don't need this account and do not want the personal information I shared about my home to remain public anymore.
my point stands though. i see no identifiable information, thus any "GDPR" claim would be outwith the remit of GDPR.
unless, of course, the persons full name is "User_789".
pictures of the inside of my home and also described details of my location would not be deemed as user identifiable information. even your full address alone would not be user indentifiable information. all the photos posted by "User_789" are of close ups of sockets on a wall. me thinks the OP doesn't understand what GDPR is.