Thanks for the speedy reply Graham, really appreciated. That's madness don't think I've ever received an email or communication about this other than to tell me they were upgrading the appsuite a few years back.
If this helps anyone else I've managed to trial a mail service called mailbird with my old ntlworld login details and its syncing everything from the inaccessible account now.
Thanks for getting in touch. It isn't linked to an active account anymore, though this has been the case for quite some time and I certainly don't remember receiving any communication that the account would be closed, on the contrary there were emails when moving the account to the newer OS / appsuite.
I guess that's where my annoyance / frustration now lies. Frantically trying to update several online accounts I have with a new email address. For anyone else in a similar situation the software / service I found and mentioned has helped otherwise I'd be at a complete loss with some online services I need access to but you do have to pay for it and I'd rather just switch away now.
Pretty bad to just switch this off IMO without any recent warning or giving me chance to move all my accounts.