How to access established (older) email accounts

Like many I needed to access my Virgin Media account to try and fix email issues.

After being a customer for over 30 years I had multiple email accounts and now I am struggling to access and fix even 1 off them.

When did the system change to the new VMO2 account and password login?
Did I miss any information or has this just been very poorly communicated, or even communicated.

How does this new system work, what needs to be done to access my Virgin Media account and old ntl world.com emails?
I used to have a email linked to my account and from there I could see 5 ntlworld.com email addresses.
Now I can’t see or manage anything on those email accounts. 
How do I add those addresses and change passwords?

I try to set up a new VMO2 account but it goes around in circles and doesn’t complete,  why?
Do I need another non ntlworld email account to set up and access my Virgin Media account and emails? This seems crazy.
When I even try to login or create accounts using some of my email addresses they are not recognised as if they don’t exist, yet my older iPad can still access and download messages?
Some accounts just constantly give error messages regarding VPN, or access via another machine, error IDF-12B. How do I get around this when I’m trying to set up a new iPad for daily access?

I don’t have any O2 accounts, only a Virgin Media account and products. 

Where are the instructions, how do I get help to fix my accounts and access?
Does anybody have definite working instructions.