can't access emails for ntlworld account

I have 3 ntlworld emails, 2 of them stopped working a few months ago ( I use outlook to open them) After going round and round in circles I had to reset the password with a very long code which worked on my phone but took another few days for it to work on computers!

Now the 3rd one (my Son's) has stopped - the original password nor the long code work - I have requested a new code but that hasn't worked either. We get "The entered credential or authentication information does not work or are no longer accepted by provider. Please change them" on the account setting on virgin media - tried putting in various passwords and get "Error the provided login data to access e-mail server imap.ntlworld.com seems to be wrong. Please correct them." On outlook it says he has to sign in to the account but every password tried comes back with "sign in failed, something went wrong while setting up your account - please try again"

He has some very important emails about holidays that he now can't access.

Can anyone suggest a solution please