Unhappy client regarding service

I got a call from MTN a while back where one of their employees called me and asked whether I would be interested in free data and airtime where my contract payment would stay the exact same amount, nothing more this is basically free and I agreed. So end of the month I got an Sms saying I must pay R462 and my normal contract amount is R330. I then called them and asked what the problem is. I spoke to a male and he looked at my account and told me that I have a new subscription on my phone that's why I have to pay exstra money. So I explained my situation to him and he said that he was going to stop the subscription and that I should only pay R330 into their account. I then got an email stating they would investigate. I then got more SMS's from them where they said they that my account would be suspended if I do not pay the extra R132. They then suspended my account I called multiple times and emailed them multiple times and today I then received an sms stating that legal actions would be taken against me. No investigation, nobody was willing to listen to the recorded calls from MTN and see that their employee **** to me, or did not explain the terms and conditions thoroughly. I called and emailed again this morning and spoke to a female who refused to put me through to someone who can assist me. Just wanted to arrange payments and get the problem solved. This entire situation has been emotionally and physically draining for almost a month now.