MTN Upgrade service

I am disappointed in MTN service. I was called for an upgrade on my existing contract of which I took the offer cause I was interested in getting the data plan. I was then surprised by the MTN debit order of which was R2k of which it was nowhere near the agreed contract amount. I called my bank to reverse this debit order as it did not relate to anything I am aware of. MTN has since suspended my service, I then called MTN only to be told that I am in arrears with R2k of which it is the upgrade fees that I was charged. I was never informed of any upgrade fees that I have to pay, of which if I was informed forehand I was rather gonna take another contract as compared to upgrading as the one I upgraded was supposed to reach the end of the term this year. I am disappointed as currently I can't even do anything as my sim is suspended