FED UP WITH MTN AND UNSOLICITED SALES CALLS

I am fed up with MTN phoning me to upsell on my contract. The consultants are rude, talk over me, speak very fast about what they are offering in an attempt to confuse. Today a sales person misrepresented the value of my current contract, offered me way more data and calls for just an R8 increase on the misrepresented amount. I am sure in an attempt to confuse me. When I exposed her mistake and told her I didn't want to take her up on her offer she said "you could have told me sooner" and slammed the phone down on me. I don't know if this is ********** or if MTN has badly trained and aggressive sales people but I am fed up with these unsolicited and aggressive calls.