3 have given me a awful time, ohh and a black mark on My credit rating!

Old_Gold

I would email the CEO explain what has happened and ask for his help to sort this out. If you show willing to remedy the situation then it should be a plus for you if you have to take further action. If this does not work in your favour then email again stating that you are taking action against 3 and seek help through the various institutions that exist. Too much onus these days are put on the customer rather than the organisations concerned.
Are you saying that since you moved there has not been any usage at all on your phone? If there has not and with the story you have told if this went to court logic should show the picture that your story adds up more than theirs. And if they do not co-operate with you dont give in to them and dont go through customer service as for issues like this they are more than useless for you.