Charged for NO SERVICES

After 4 years I am told by Virgin Active that I owe them R1+k for the year 2012. I had a contract for my son who resided in Boksburg for his high school years, he finished matric in Dec 2011 and moved to Jhb. I cancelled my contract with a lady in the Boksburg branch. He now wants to join Virgin and they are telling me to pay this amount or 50% thereof for him to join. They can't show me anywhere that any of us used Virgin active during 2012 and according to them I never cancelled....WHICH I DID!!!!! I feel this is a money making scheme....he was with a professional rugby union in 2012 and 2013...why would I keep the Virgin Contract???? And the lady at customer services couldn't be more rude and unhelpful~! I am disgusted!! Why join them ever again??