MTN - FAILING - BLACK-HOLE IN SPACE

Upgraded my data contract in OCT 2019, with monthly billing of R628 a month. Since FEB 2020 Mtn went over to a new system and the billing for this contract tripled. Ever since then I have been lodging queries for the billing to be correct. Last month MTN deducted R6000.00 out of my bank account due to the billing still not corrected. Every month I have to return this debit order at my cost with the bank and pay the correct amount. Today I have received another bill for a further R9000.00. When speaking to their so called service champs it is either i can thelp you the system is down or I can only give you a reference number and escalate it to the billing department. I a beyond frustrated with MTN and their ability to address matters when they are at wrong. I asking for someone to please help me... I really don't know what else to do?? This is costing me time and money and a lot of frustration. At the end we are continuously fighting with the hope that there are some bright spark working at MTN which will help.