Wrong bills and ignorent

Kathrine called me in the middle of august selling a moderm with 2Gb data only simcard for only R120 per month for 12 months. Their first invoice that they sent to me, i was billed R70 but i paid R120 that we agreed upon into a standard bank account that was sent with the invoice yet in september i was charged for not paying the previous month and i was over billed too, i paid R384. I wrote an email to their customer care and i was told that there were things that were never explained to me over the phone when i took the contract. I kept on recieving sms saying i am left with some airtime on the simcard, i called cellc to ask about the origin of the airtime but cellc said they cant go into my simcard, i then called mweb technical suport team to ask about the airtime and i was told that there is no airtime in my simcard there is only data and i am not in an option of recieving more than 2GB per month. The following month i was billed R498 instead of R120 again, i wrote an email to them but they told me that i exceeded my monthly limits and i told them that i am not in an option of exceeding my limits and i agreed upon data only and they never respond to my complains. I have written