Inaccurate Unauthorized Billing

I app**** for a new contract in April 2015 and requested a limit of R300 to be set on my contact. The MTN sales consultant actually set up a limit of 11500 which I was unaware of. I was changed R2500 extra for Data excluding calls. The consultant was dismissed and now MTN says that they cannot refund the amount due to the contract been signed with out a limit. The actual limit of 11500 is ludicrous its been 4 months and Im <br> held liable for a bill which I'm disputing. I was a Vodcom customer for the previous 9 years and thought that MTN was a better option they thrive on out of Data bundle rates and charge absurd amounts. I will be canceling this contact. Should of stayed with Vodacom