Hi
I had a similar situation a number of years ago, won’t bore you with the details, however; suffice it to say the mobile phone companies’ opinion and mine differed.
One thing I would always recommend, never do anything over the phone, always in writing and keep copies.
In my case I responded to each and every letter with the outline of the case from my perspective and defending the claim against me. It seems these people all come from the same mould as they tend to totally ignore anything you say as they believe they cannot be wrong.
Simply state your case in writing, explaining exactly what was done, be it by letter or phone call and to whom this was made. Highlight the point that this, to the best of your knowledge and belief had been settled 8 years ago. (an exact date would be much better)
In my particular case they tried to overcharge me and went through at least 3 different solicitors in the process. Each and every one of them was told exactly the same thing; in fact I used the same letter, simply amending address details, date etc.
Eventually they gave up, which was the good news, the bad news as such was they then decided to report a default notice to a credit reference agency. As best as I can tell, all this did was to make the bank ask a few extra questions when I went for a loan.
You can get your credit report and if a default notice has been issued, you may have the right to have attached a note which explains your point of view. The default notice would normally be removed automatically after three years anyway.