Billing Error and Poor Customer Service

The MTN South Africa has charged me triple the amount and when i called the billing department (Shamina Manuel) tried to assist without any interest as she put me on hold for very long after confirming my detail and when she came back she is requesting my contact with MTN whilst acknowledging the problem she said without contract she wouldn't be able to assist. She even tried to teach me a lesson that i should keep the contact for 2 years. My account number is A***. hoping to get assistance from someone better equipped in dealing with client.