MTN fails to do a SIM swap

I'm so disappointed by MTN that has failed to do a SIM swap. My phone was ****** . I'm a student with Unisa so that have contract with MTN to assist with data for exams. They asked us to buy new SIM cards and smsed the student number,new number and the old number that I use with Unisa.They loaded the data on my old number.after few days my phone was ******.Now I'm struggling to get my number back MTN said I must wait for the letter from Unisa and we are on level 3 lock down universities are closed therefore I can't get my number back.I just want to go back to prepaid rather so that I can be able to get my number back I don't want their data anymore cz it's a disaster to be in contract with them.Unisa and MTN must find ways to assist in such cases we cannot battle like this just to do a SIM swap bathong.