Horrible service received

I app**** for a disk from MTN Momo license renewal on the 22nd of December 2020. They were unable to assist me and promised to refund back my money, I send my bank details to them on the 24th December 2020 and then they always tell me that I will get my money within 3 days but I am not getting it. I don't understand why they keep on promising that they will pay within 3 days and not pay. I communicated with them via their chat and via email. I ven informed them that I will report them if the don't refund me and it didn't help. I am waiting for refund for DD77WPGP AND DD79PWGP