Incorrect Billing and Correction of Invoice URGENT

Try and get a billing Statement sorted out that has been incorrectly billed!! This is ridiculous after I had done an upgrade, I have spoken to 5 call Centre agents and even sent through an email, my upgrade was done early but my billing for Sep and now October is incorrect as I am not being charged for my old device, I need my billing to be corrected and this is an absolute disaster! I am so dissappointed in the lack of getting hold and trying to get this fixed as a matter of extreme urgency. I expected this to be sorted out already its been over a week let alone the loss of income on my side due to this error this has to be dealt with today and a correct billing statement for both months to be issued can a senior person at MTN sort this matter out! Let's see