Waiting for almost 2 months for a bill

I received my bill for September and it did not include any of the contract discounts I receive on a monthly basis. I called MTN on 808 and requested that it be corrected. I was advised that it would take 5 to 7 working days. I then called back after 10 and was told 10 to 12 working days. I then called back and was told 15 to 21 working days. I then fell into the new billing cycle and had to organise a form of payment plan so I wouldnt get disconnected. I was told it had been escalated and would be dealt with asap. I followed up twice and it wasnt done, and I called again now, and was told by the agent that it has not been attended to. I have 7 reference numbers and have spoken to countless agents and supervisors. I am now being told that they cant even give me a reference number anymore as they arent actually doing anything more. I must just wait. I have been a loyal customer of MTN for over 15 years and am disgusted with this level of service for a simple invoice. You should be ashamed of yourselves. The system seems to work fine to send me notifications to remind me to pay, but you cant even send me a correct invoice after 2 months and probably 15 phone calls from my side.