MTN store Vanderbijlpark,river complex is ****!!!!

I signed a contract for R30 airtime in Vanderbijlpark MTN the river complex ...the lady stated that the contract is only R30...monthly I've been billed R250...I called MTN and they state they can't assist,as I've signed a R250 subscription.... MTN supports the mispresention of theyre sales agents ....on my hard copy contract states R30 but debt order is waaay different.....now I'm in arrears and MTN wants me to pay 2k for they on fault ....****ty service from the customer care agents marven is his name......i want my contract cancelled with this network provider..they have even blocked my line...!!!!!!