Poor Service- Logged tickets closed without resolution

I logged a call(1-***) requesting for invoices/statement for the periods March 2018 to February 2019 and March 2019 to February 2020 for my personal tax return on 20 February 2021. I called the contact center on 02/03/2021 to escalate as I have not received any feedback. I again called on 10 April 2021 to follow-up only to be told that they have made the second fiscal period information available and logged another call. I insisted that they retain the original call as the call was not resolved and the call will start with a new aging. Unfortunately MTN do not e-mail invoices like conventional entities and expect you to login to their portal to retrieve invoices. The invoices from the portal are available for a short window period. These should be available for a period of at least 3 years. document retention period is 5 years. I have provided MTN with a deadline to provide the necessary information. I am already considering not renewing my contract that expires within the upcoming months.