Mail server Password and crazy user situation.

I am trying to use Thunderbird Email client to connect to my virginmedia.com mail service.  Before I begin some background on the crazy Virgin arrangement.  So, when we first signed up my wife and I we had accounts on blueyonder.co.uk.  (Seem to remember Virgin aquired this). I have an account like g1@blueyonder.co.uk and wife say s1@blueyonder.co.uk.  g1 is the main account for control fees etc. When Web Mail came along Virgin put me on my g@virginmedia.com account.  It is to virginmedia.com mail server I am trying to connect.  Hotmail account goes in automatically no problems.  But my VM.com keeps saying wrong password or settings.  I set my password on g1@by.co.uk and g@vm.com on the Web.  I have all the PORT settings and DNS names for virginmedia.com both IMAP, POP3, and SMTP.  Even manually I can't get it to connect.  Here is my question.  Maybe setting the g@VM.com PWD on the web doesn't set the PWD on the VM mail server?????    If so how can I as a user set it?  As g1@by.co.uk is authorative  How to I get to set the Mail server password for VM.com from by.co.uk.This is a crazy situation.  I could ring help desk in SA.  But will a front line Help Desk really help me?  I am so fed up with VM for Email.  I have my own DNS with Email and use IONOS and get a good Email service at very low cost.  I only stick with VM as the broadband M125 is good and reliable.