I received a letter yesterday from a company called MakenzieHall in Ayrshire asking a Mr <My Name> to contact them regarding a personal matter and that they believe I reside at <my address>.
I have never heard of this company and was a littler perplexed to find they were a debt collection agency when googling them.  Their letter head made no suggestion whatsoever of what it is they do.  
I rang them back this morning to find out what was going on and to my shock they informed me that I owe Carphone Warehouse over £650.   Bearing in mind I have had an Orange contract for nearly eight years (March 2013 will be the end of the eighth year) I had no idea what he was talking about.  
When I was 18, in 2004, I took out a contract with O2 from the Carphone warehouse.   At the end of the contract I cancelled went to Orange, as they were offering a very good deal at the time.   At the end of the CPW contract I was not in credit or debit with CPW, I was paid up and the contract was terminated.  
Apparently not.  This debt collector has the contract as 'involuntarily terminated' although he has no date for when this occurred.  They also have no information as to how such a biblical amount of money has been accrued from a £25/month mobile phone contract.  
At the time of switching to Orange I lived with my parents and both mum and my step dad cannot recall any letters from CPW or O2 regarding this matter.   They still live at this address.  
I have lived at several addresses since and have never received a letter, or any other communication, regarding this matter.    I have been traceable as in 2007 british gas caught up with me for an unpaid bill at a previous address.   I know how these things work and I know how easy it is to trace people 'off the radar' as I used to do it for a living.  Therefore, I believe that if O2 or CPW wished to pursue me, they could have with ease, or at the very least given the job to a debt collector to do it for them.  
So having heard nothing for eight years or so this suddenly appears out of the blue.   When I spoke to the debt collector they were keen to go though my income and outgoings with me, and pushed the point until I quite rudely told the guy that I was handling this phone call, not him.  
So as it stands now, I apparently owe £650 for a debt I didn't know existed for a service I terminated and no longer have any paperwork for. 
Carphone warehouse will not deal with me as it's 'now in the hands of one of their specialist contractors' so I cannot obtain information there.   One thing which did occur to me though was a Freedom of Information Request, I presume they have to abide by that?
Now there is no way I'm paying up as I don't feel I'm in the wrong and short of CPW/O2 not cancelling the contract, or at least with their accounts department, I don't see how so much money could have racked up.   I have little information to go on and this genuinely has arrived out of the blue. 
So OCUK, what is the best course of action?  The debt collector has already put a 'contacted but refused to deal' marker on my 'account' although I have managed to get them to give me two weeks with the account on hold to find out what the hell is going on.  
I really don't want this to cost me anything so proper legal advice will only be sought if no other option remains.  
Thanks