Not delivering on what the promise

In February 2020 I called MTN to cancel my contract with them, i was transfered to to retentions where instead of moving my contract to prepaid they made me an offer that made me not cancel my contract and i took it. I received the data they offered me only for that month and March if im not mistaken. In April i received data from Wits since im a student and didnt notice that MTN did not give me the data that im paying for.

Last week i called MTN again to complain about my data, the lady at retention told me should would investigate the matter and get back to me within 24 Hours, days have passed now and still no feedback from MTN regarding my data...