my email is no longer accessible on my iPhone

I have the same problem, my email is no longer accessible on my iPhone, nor via my VM02 account - I have the message The entered credential or authentication information does not work or are no longer accepted by provider. Please change them.  I have tried to change them, but it just doesn't work.  I have tried to add the email to the VM02 account (which still has my old email address as accessible) by linking it via oauth.virginmedia02.co.uk, but it takes me through 10 stages (requesting link, verifying, finding my account, etc etc) and then goes back to stage 1 again.  Calling VM, you just get redirected and a link sent which is hopeless as it gives me the directions I have already tried.  I am so fed up with Virgin Media now.