MTN does not allow reversal of purchases on their mobile app

I bought a data package via the MTN mobile app and immediately realised it was the wrong data package when I received an sms confirming the purchase. I am adamant that I selected a different package and that there was a technical error on the MTN side which somehow allocated the incorrect package. I immediately contacted MTN to have the original purchase reversed but the call centre were unable to do so as the purchase was made via the app. They indicated that they needed to escalate this to the MTN app team. A couple of days later, I bought the package I wanted. MTN took quite a few days to investigate the incident. MTN now refuse to reverse the original purchase stating the following: 1) Their system show that I made the original purchase; 2) Data was already used from the original package, so they cannot reverse it; 3) They do not have system capability to reverse purchases via the MTN app; and 4) Their terms and conditions are that purchases made the app are binding.

My response to each of the above are: 1) I am not disputing the original purchase, only that I am certain that the incorrect package was allocated due to a system error. I cannot prove this to MTN, with a service manager who called me asking f I had screenshots to support my case. Now who would normally take screen shots of their purchases? 2) I immediately called MTN after the package was purchased to request a reversal. If it was reversed immediately, the data would not have been used. Due to their investigation taking a few days, there was no way of me preventing the data from being used, other than not using my phone when I was away from my home wifi. 3) Why does MTN not have built a reversal capability? This is quite suspicious - I would only think that this is done to preserve revenue. Did they not anticipate that clients may want to reverse purchases? 4) I looked through the terms and conditions on the app and there is no such condition, unless this is embedded deep in other linked pages which are included in the Ts and Cs. There is also no warning to alert the user that a purchase is binding on the front page or as you go through the purchase. Based on all the above, I believe MTN have deliberately built processes to prevent any client from choosing to reverse their purchases via the app.