Rejected without reason.

I have been a MTN account holder for the past 5 years. I have also been under debt review for the past 5 years. I've upgrade, while under debt review, 2 times during this 5 years. I'm due for a upgrade again end of Jan and was rejected without reason. Was only told to go to my nearest MTN store. I have never missed a payment in the past 5 years and even opted this time to reduce my monthly amount/contract. Can anyone or any department please contact me regarding this?