Unauthorised deductions

I took a 50 minute top up contract at R189 per month from Nashua in August 2014. Nashua folded and the account was moved to MTN. Since August 2014 to date, my debit orders have been in excess of the contract amount. I went to the MTN walk in center and was assisted by Julian Tredoux. He provided feedback to say that \a top up contract is not guaranteed"no where in contract does it say this. I even contacted Nashua (Shadrack) who advised that MTN must deal with the billing issue. 808 is a waste of time. I have sent to numerous emails to Julian and Shadrack and have given them deadlines to respond to how this query will be resolved. From 2 March 2015 until now...not one response! I want someone competent to deal with my query. This overbilling is against CPA. I will once again provide MTN until the end of this week to respond to my query and advise when my money will be refunded or I will not only embark on a smear campaign on all forms of social media but I will be sending my complaints directly to the CEO of MTN and will also be lodging a formal complaint on the basis of CPA. This utter lack of respect for clients and purposely ignoring request is disgusting! """