I can't access my Microsoft 365 Business Standard Admin account

Question

I subscribed to a 365 Business Standard account today. When I tried to add a custom domain I wasn't allowed to as another email with that domain already had a basic microsoft account. I successfully did an 'admin takeover' of the account using BI and removed the domain, I also deleted myself as a user from that account. However, I then tried to log back into my Business Standard Account to add the new domain - and it didn't recognise my account so I couldn't log in at all. Account recovery simply recovers the 'free' microsoft account, and it hasn't associated this email account with my new Business Standard 365 subscription. I've managed to confuse the system - end result is that I've paid for a subscription that I can't access - I also can't raise a support ticket as I can't log in. Would appreciate it if a Microsoft Support agent could look at this and raise a ticket for me - many thanks in advance!