MTN uses bad service providers for their clients

I have been more than 10 years with MTN, Mondo a affiliate phoned use in Jan 2022 to do a upgrade. I did the upgrade and found out on my statement later the next month there is a charge on my account of a additional R 750. I then queried it with MTN they said that they get Mondo to get back to me, More than a month later Mondo gets back to me saying they listened to the recording and said that they messed up because the consultant did not disclose to me the early upgrade fee. They said then they will refund me, today is the 05.07.2022. 5 months later no refund and i called then like maybe 30 times to follow up where there is just more excuses. I cannot believe MTN will use companies like mondo and everytime i phone MTN they said they will escalate it. Shame on you MTN