********** activity on my account by Vodacom I refuse to pay

I have 2 contracts with Vodacom one was just a sim card the 2nd was a cell phone blackberry torch. at the time of signing the contract the contract said BIS. 1 year and 6 months into the contract both my numbers were blocked. They said my account has reached its limit to which I used data. which I could not because the nr I was using was top up and yhe other was for phone calls. They said that I used 2100 on whatsapp which is impossible. and whatsapp was included in BIS. now they've accumulated a huge bill and I refuse to pay as that is against CPA. and no one makes an attempt to call me when this \bill"seemed to be exceeding it's \""limit\"". The bill is now at 4200 and I refuse to pay because this is just ********** behavior. <br> """