Virgin Active ******

Guys please read you contracts while joining these people , i joined on a 12 month contract at virgin active , what i didn't know was the clause saying after that it continues automatically. April i got a call from them asking when am paying the amount of something like 400 i was owing , i advised the lady to cancel the membership because i joined for 12 month and in any case i was no longer staying in the area . now i get a call from the debt collectors they say i owe 1000 something from virgin active . This puzzles me as i clearly said the membership must be cancelled .