Help required fast please.

After a terrible experience with Talk Talk that lasted 4 months they are now being a pain again. What happened is this:

I had Talk Talk broadband and a call package, i forget the name but it gave free international calls. Well the brodband was terrible, had to ring up every other week on average for help as it kept disonnecting, or days on end it wouldnt even work. By November I had had enough of this and rang them up and said a they wernt providing there end of the bargain and not providing a consinstand service, and not being very helpful I wanted out of the contract. I said that I wanted to talk to the complaints department, which I promptly got put through too.The complants chap was English, I explained what had been going on, he was very understanding and said that the contract would be terminated, he said the call was recorded, he gave me his details at the time too. I thought this would be the end of this.....

In January this year, I got a phone call again from Talk Talk saying that we owed them for ending the contract early, I then politlely explained to the person that we ad already had this confirmed that we wouldnt owe any money by the English chap, and the call was recorded,I gave him the time and date of the call, he said thanks and i thought that was the end of it......

Now today I have just had a phone call from a debt agency saying Talk Talk have instructed them that we owe them money. Any advice please before I cll Talk Talk next please.