Virgin active contracts are for life

Nearly a year ago I cancelled my contract with virgin active. I had to go in 3 times to be able to cancel my contract which came to an end. They stopped the debit order from their side and in everything went well. Now suddenly I get phoned by their debt collecting company, nearly a year later , *********ing me to black list me if I don't pay them a minor amount of R700. If I owed them money,why did they cancel the debit order,why was I never contacted,why was I only contacted a year later?