I, too, cannot add subscriptions.
The same issues others are describing.
Suggested method in their video just isn't my experience.
Always get the 'oops' message.
Anything I try through My Virgin Media doesn't work.
(The Stream section just isn't functioning; if you can find it)
I'm directed to "chat" which is fine if you have hours to kill, and they can't help if you manage to chat with anyone.
If you're put through to Technical, just sit back and wait.... You will never get anyone to chat from technical.
If you call and manage to get through, they don't know how to help.
I've had a number of promises that they will add my subscription, but NOTHING CHANGES, even after reboots, etc.
2 days of trying and I still cannot add a subscription, even if you get someone who actively tries to help (oh yes, I've had my share of them hanging up on me).
So I can only agree with others: We are BETA testers on a new system that isn't ironed out, no-one knows about and just isn't living up to promises.
Hey-ho, same old Virgin Media!