WRONG INFO GIVEN FOR CANCELLATION OF CONTRACT - NOT HAPPY!!!

I recently requested a cancellations quote to cancel my contract from MTN and was told it will be R5570.10 . Now when I phoned the retention's department I am being told I have to pay an additional R10 755.42 before they can cancel my contract. This is UNACCEPTABLE! I am really upset and disgusted by this. The agent that sent me the email should be liable for this balance as she quoted me incorrectly. I need someone in MTN HEADOFFICE to do this cancellation for me now. Or the lady that assisted me with this quote should be liable to pay this balance on my contract as she did not give me the correct information. I phone MTN headoffice in regards to this matter and the lady said she will phone me back - I am still waiting. The reference for my email to Retention's is ***. I am NOT paying MTN this extra R10 755.42 as I do not have the money for this and it is not my fault that I was quoted incorrectly. MTN does not even deserve a 1 star rating. I wish I could've given them a 0 star rating. I will not recommend them to anyone that I know. SOMEONE please sort this out URGENTLY. I need this cancelled and I repeat I am NOT paying this extra R10 755.42 to MTN. You have to make a plan to cancel this.