Unable to link Virgin Media account to Virgin media o2 ID

I can’t link my Virgin Media account to Virgin media o2 ID. I’m a new customer with internet set etc. set up. I’ve previously had an account with Virgin but have tried the email it was linked to and it doesn’t work. I’ve tried doing this in incognito mode, on a laptop and mobile but it still doesn’t work. I’ve tried doing this with both a gmail and an outlook account.