Mtn extra funds debits and no refunds done

I have been a men customer with a contract for over 10years ,the past year when I took out a new contract and signed documents to money agreed upon,however they always take a higher amount.Ivw tried calling and complaining but no assistance I pay more that what was the actual contract.There was a time where they took an amount of 1700 and was told they will refund until today no refund was made.Last month I missed an instalment with them I called and made an arrangement for a double debit on payday.I then also received an SMS that I should go in-store and pay it cash of which I did and same day a double debit went off.So it's 3 instalments.I called Customer service and spoke a gut called Andile Chili who also confirmed that he could see the amounts and a refund will be made.He gave me his email and requested a confirmation I sent to him and he didn't respond .I tried to even resent the same email with statement to him and also the complaints division up to to now ,I still haven't received a call or any sort of response.I request for my money to be refunded ASAP.I am no longer a happy customer with MTN,1year I misplaced a phone and insurance told me I'm not insured and I let it go.Im enough of this poor service