Lack of honesty during sale.

Oh what was I doing taking a call from an italk agent offering me an MTN router and accepting it?! Now I'm stuck with a bill that is more than what we agreed of, I asked her will I be paying the agreed R329 month end and she said yes and now it's above that and there's a prorata that MTN doesn't want to hear anything from me about, they just want their money. Firstly, she said I'll Rica the Sim during delivery, first red flag, I had to inconvenience myself and look for an MTN branch to Rica the Sim then now the bill. I emailed italk and they haven't responded. MTN wants their money month end and the debit order will definitely bounce and ruin a credit score I worked so had for. All because Ontlametse Diokana wasn't trained on the principle of honesty in making a sale. They just chase sales.