I have tried to log in to MyVirginMedia, but the other problem I'm encountering is a doom-loop of screens which make it impossible for me to log in.
What is the doom loop you are experiencing when trying to log into your online account? It may be due to the home move.
Virgin Media systems always create a new account for home moves. (When a customer moves the account number changes, the account number sits with the property and not the customer)
Homemovers should have created a process called 'Move and Transfer' which would move over your current email address (es) and also update My Virgin Media allowing you to continue and log in as before the home move.
If this hasn't been actioned then a member for the foum team may be able to process this for you. however it may be a couple of days before they pick up this thread.
Providing you haven't made any changes to your package or equipment then your current pricing and remaining minimum contract term are carried over to the new account. This isn't always reflected in the new account due to VM's antiquated billing system, and may need to be manually updated.