Poor Service from MTN

I have paid my account manually for R2200 and they also debited my account for R2000 i have logged the query they resolved without a solution or comment. Followed up the consultant told call has been re-opened emailed again with proof of manual payment but still no response. I went to the store to log the query again this morning they telling me that my manual payment has been paid by someone else and my account is in arrears on 2620.28 but i have paid an amount of R4200 end of Feb. I am not happy with MTN i have been following up with then since beginning of the month till date no resolution.