Vodacom - Refusing to cancel my month contract

Ref Account no - <br> <br> Out of the blue Vodacom billed me ad additional R3,477.87 over and above normal contract price of R149.00 for my 3GB month to month agreement with them. Invoice dated 03/05/2015<br> <br> Not once was I advised that my limit had EXCEEDED. The last sms I received from them ever only showed a 90% usuage.<br> <br> I tried to cancel my month to month contract with them and they refuse to do so. This is *******. So they are adding a monthly fee every month on top of this outstanding amount which I cannot afford to pay. I believe that this data usage has been \made up"by Vodacom or my account has been used **********ly by them. I want my account stopped immediatly because althought you did not allow me to use data on a monthly basis because you have blocked it"