Cell C poor customer service and false advertising

I just went to upgrade my Cell C contract according to the TnCs of Cell C I have met all their requirements only to be told that I can't upgrade due to a credit issue. My argument is this why make such TnCs have your customers meet the requirements and then decline them because belive you me if anybody listens to the TnCs you will hear nothing about credit issues. So I guess Cell C wants to chase away all their loyal clients because of false advertising. I am disgusted in the way Cell C treats a client of 20years really such poor treatment. I've never missed a payment or had my number suspended when it came to Cell C everything was on point and now to treated like a newbie is not on. I hope someone higher in Cell C will have the decency to phone me.