Over charged

On the billing of August i was overcharged. I had an upgrade and signed for a monthly bill of R562.00. Then i was charged R1060.00 on the first month of the contract. I have been calling the call centre and sent from pillar to post but nothing is happening. I have 4 reference numbers for one complain, Ref 1: ***, Ref 2: ***, Ref 3:*** and Ref 4: REQ***. Everytime i call I'm being told one thing tha i need to provide the correct Cell Number. And it puzzle me because that is the first thing they ask before you lay a complain. I have spoken to about 10 people for one query. is it that difficult to refund me if i was over billed or just let me know why i was charged almost double what i must pay..... Can someone who knows his/her job at MTN please try to resolve this because i feel like throuwing them with this stupid phone and change my account no....