unhelpful consultants, stuck wiith bad upgrade

I tried to upgrade with MTN over the phone. Later received a text stating I had upgraded was told my phone would arrive in the next few days, a week past and nothing received. I went to one of their branches and was told the upgrade was done without a phone, and that they couldn't fix it from their side. I called to try to cancel the upgrade but was told the lady who did the upgrade was busy and that they couldn't help me, was told each time I called that she would call me back and that they would send her an email. She never called only reloaded data and sms bundles to my phone. I'm now being billed for it together with an upgrade and promo service fees. This can't be right my bill is r650,I shouldn't have to pay for this.