Misrepresentasion in advertising

I upgraded my MTN contract in September 2015. In their Yello Trader (Spring Edition) my package was advertised with 500MB per month free for the first six months. After three months (December 2015), they decided that my promotional period is done and hence I didn't receive anything for that next two months (January & February 2016). Calling the call centre is a complete waste if time. One only speak to someone who \escalates\" the problem. NO FEEDBACK!! You have to call again, and the person who dealt with the query only left a silly reply on the system that even the operator assisting you with the call, doesn't even understand. MTN, I aske you very, very nicely...... Please give me my promotional data. I don't want to call your call centre again!!!! Sometimes I feels as if I know more than the people you employ!! Your systems of providing feedback are also completely inefficient!!!!"