I don’t recognise the card added to my virgin account, can’t change it because my accounts won’t link.

Hi. I’m currently waiting for my virgin media to be fitted. I’ve had emails come through with my account number, and my email, yet the bank account the bills will be directed to is not one I recognise. I can’t change any of the details, as my app won’t allow me to log in. It says that my accounts aren’t linked. I can only assume it’s because I am a prior customer? Any help at all? I see a lot of people seem to be having this issue of accounts not linking. Thank you.