Bad service

MTN is a big **** and *********** us as customers, I have been their customer for the last three year, having paid my installment on time on the 20th and at times checking my balance which never changed for approximately 1 year, from start I paid upfront by 5k for an 17k device by that time , this month I requested a settlement before that on the same month of April I paid 2000 on 04april25 at mall of tembisa which they told me to call retention to know how much I should pay to settle this account, ***, which a lady at retention said my settlement is 1136.74 and even got an sms of cancellation on a day, now I went to the store to request for my paid up, they are telling me is still active and an amount of 2500 is required for early settlement, I was told to call 135 which a lady called kabelo makgamatha told me that is still active and 2500 is required and she has sent it for investigation, but as all calls are recorded I need MTN to sort out this matter urgently