INVOICING AND STATEMENT NOT CORRECTED

I am a loyal customer for almost 33 years. MTN IS REALLY NOT LOYAL TO ME. At last my upgrades was done. Starting to receive my statement, I see that I am overcharge on each account for recurring bundles. Since upgrading three months ago on one contract they gave me some credit but still did not correct the account. the second account have the same problem. they keeping on charge me for recurring bundles that is not in the contract, I keep calling in every month to get it corrected but still nothing get corrected. All i ask is that MTN must please correct my statement and invoicing according to my contract. Very disappointed with MTN AND MONDO