Wished I'd never used virgin

Hi I ordered virgin media for my son who has learning disabilities as he's had it at ours but has now moved into supported living.. I'm struggling to remember the memorable word he's new bill is incorrect no surprise there but I can't speak about this as they can't get into the account soo how do i give virgin the power of attorney details to discuss this bill why does virgin make things so difficult I can't get hold of Natalie who sold me the package surprise NO Goes straight to ansfn I even know where the mistake occurred BUT can't get into the account please anyone help I know about the two month charges it's not that either....