MTN Overbilled me for months with reason!

This is the worse company ever to have a contract with, I have been overbilled for multiple months and no one could tell me why I am overbilled, I called and also chatted with MTN on social media I also emailed the complaints at MTN and non could give me answer, all the consultants gave me a run around and others made excuses just to get rid of me, I have been over billed so many months and it's really a big problem because I sent MTN my bank statement and my bills I done on their app and they still can't tell me where the extra bill is from, my account is always over billed they even send me bills for 2 months, they send me a bill for the current month and the following month, when I asked everyone at MTN no one could answer me when I asked why my charges are different, I am disgusted by the MTN billing system because they rip me off for many months and they *****ing my money and I just paying them because I don't want to have a bad credit score, so I am forced to always pay a high bill every month, I regret ever taking a contract with them supporting them for the years I supported them.