Package downgrade

I’ve been a loyal customer of MTN for over ten years, but my recent experience with their service has been appalling. My contract came to an end a couple of months earlier and I’ve been on a month to month since then. I was contacted a few weeks ago by one of their 3rd party call centers to renew my contract which I did albeit on a lower package based on the assurance that I would not forfeit my data or minutes accumulated at the time of the downgrade. However, when the new billing cycle kicked in, I was surprised to see that the agreement was not honored and my balance was reset to zero, only reflecting the minutes and data of new package and month. I’ve spent significant time on phone calls to address this with customer service and the retention departments, but to no avail. I’ve been transferred from the one team to the other as well as what I believe to be the 3rd party call center who just referred me back to MTN. It has been an absolute waste of time! This either needs to be corrected as promised based on the new contract or I expect that my old package be reinstated with the correct balance. I am being sent from pillar to post with no resolution in sight. Calling customer service to follow up has not helped nor sending emails to the various departments.