Incorrect Billing - Bad Attitude

I have a contract with Virgin Active (Discovery Vitality). My membership fees gets paid via debit order. On 12 October I receive an email saying my account in in arrears with an amount of R194.50. I found this very surprising as my it goes off by debit order every month. When I phoned the number on the email I spoke To Norman Stripp who told me that is was for my daughter Mia's V-Club membership fees that was in arrears. I told him that this was impossible as on 17/09/2014 we signed a 12 month contract with Sethu at Meyersdal Virgin Active. We paid this in full - Cash. He told me that there was a price increase in January 2015. NOW - if I understand this correctly we signed a 12 month contract and paid it cash and in full how does a increase effect me? He got very arrogant in when I told him that it is because of issues like this that people cancel their membership. He asked me if he should go ahead and cancel my membership??? He mailed me a copy of my contract. On this contract is states is is 12 months and COD - nothing about any increases??<br> <br> I find the staff very rude and as far as I am concerned I do not owe any money