MTN is ******** prepaid customers

So disappointied with MTN *******.I am MTN prepaid user everytime I recharged airtime R40 gets deducted from the airtime I have purchased.I contacted the call center and I was told I joined mtn games which I'm unaware of and I don't even know the benefits of joining those games that deduct from my account and I don't even know how to join them...MTN is ******** customers with those so called games...It's pathetic.