Billing og canceled line

I canceled my domestic telephone line during February 2015. After numerous calls the line was only canceled during May 2015. The line was billed since then to date. the billed amounted to R 1119.70 to date which I refuse to pay. I received a refence number*** A the first time which according to customer service does not exits on their system. The second refence number is ***A. How can you pay for someting that you dont' have?