Poor and pathetic service

I have a cellphone contract with MTN and I cannot access the June tax invoice on the MTN App and when I call MTN I am told that the invoice is blank, I have been calling for 3 months and opened a total of 11 Service Request for the same thing and it is still not resolved. Here's the list of Service Requests opened since then:- 1. *** 2. *** 3. *** 4. *** 5. *** 6. *** 7. *** 8. *** 9. *** 10. *** 11. *** Every time I call I am told that a ticket will be opened and that this will be escalated, after that I get the same kind of email "Dear Customer, Your query *** has been closed. Please contact call center if you require more information. Thank you for using MTN. Have a Y’ello day". So I go on to myMTN App and nothing has been resolved, I call them again, same story, I have even asked to speak to their Manager, but I am always told that "the Manager is busy on a call with another customer and will call you back" but that never happens. I have used MTN as my preferred service provider for over 20 years on prepaid. My 24 contract is coming to an end in November 2023 and I have never missed a payment since it started but I have to beg MTN for an Invoice for 3 months. Needless to say, once it expires, I am moving my number to another service provider and I will take up a new contract with that service provider. I AM VERY DISSAPOINTED!!! Regards AS Ntaba