Overcharging hidden costs

I recently responded to Mtn's text message that im due for an upgrade. On my arrival to there store in Greenacres Shopping Centre in Port Elizabeth a Sale consultant Amanda approached me and help me with my upgrade choice. After I decided on my upgrade I clearly indicated that Amanda should discuss all charges with me upgrade fees any charges involved in the upgrade process. I was told my upgrade fee would be R105.00 and my contract fee a month would amount to R150.00 a month after being assured that would be the only charges, I got the shock of my life on the 20th of June 2015 when MTN deducted R 1029.00 from my account!!!! I went into a state of panic cause my car and my house bond still needed to go off and this was not calculated in my budget. I Phoned MTN 3 times regarding this overnight theft and was told it would take seven working days to reverse the over charged amount im still waiting??? Ive been a contract customer of MTN for six years and this Iis how they treat their customers. I took reference numbers and names of all the times I called and will escalate this matter to my lawyer's now, because MTN clearly do not intend to give back my money. Absolutely unacceptable.