overstated amount deducted from my bank account.

In April 2015 I did an upgrade for my 11 year old son, I was previously paying R169 per month. This time he opted for a new Alcatel (Iphone look alike) which was cheaper an I signed a FIXED contract for R129 where he would receive a fixed amount of data, free minutes and SMS per month, NO AIRTIME is given on the contract that would need to be purchased.<br> I signed my Debit Order as per usual for R129, end May an amount of R461.14 was deducted from account, end June an amount of R365.62 was deducted. I am waiting to see what July holds for me, I want my money refunded IMMEDIATELY!!! <br> I tried resolving it with MTN, contacted the call centre, held on for an hour and 8 minutes and have sent numerous emails to customer care and I am getting no joy.