He has told me to just ignore it, although I'd sooner send the letter mentioned earlier in the thread and know that they have stopped chasing me.
Firstly, I'm only going from memory here, so I will reiterate my earlier posts.
It is great for people to post helpful template letters, but you'd be much better off visiting the sites that they have been taken from, such as ConsumerAction, or MoneySavingExpert. There you will be able to read up on the various situations that they apply to.
Now in layman's terms, the original letter was sent to you to try and establish that you are the owner of a particular debt.
You were under no obligation to phone them, and indeed are under no obligation to reply to any of their letters (at this point). If it did go as far as court action, then obviously you would then have to start taking things seriously, but at the moment they're just 'fishing' for information.
So you can ignore them, but the
will continue to harass you via phone and letter. Their correspondence will likely get more and more threatening, but ultimately will (likely) be hollow threats.
Or, you can reply and state your rights (of which you have many).
Firstly, they need to establish that you are the 'owner' of the debt. If they can't do this, then they shouldn't be pursuing you - you're under no obligation to help them. There are template letters about this on the sites I've already mentioned.
Secondly, they need to prove that a 'valid' debt does exist. To do this they should be able to provide a copy of the original agreement. Again, there is advice and template letters relating to this on the forums already mentioned.
Finally, I'd point out that the above advice is just from my memory of being in a similar situation. I sent a template letter (taken from MSE, or ConsumerActionGroup) and they immediately replied and agreed that they would drop the matter and cease correspondence.
So as I've said, letters such as the one posted by Mejinks are good - but there is so much information available, that you really are best reading up on a specialised forum. There's actually been a lot of good advice posted here by various people (as well as some not so good), but if you want to get these people off your back, I really would advise an hour or so on the specialised forums that have already been mentioned.
If you do decide to send a letter, I'd advise getting it checked over, either on here, or better still on ConsumerActionGroup, or MSE forums.