Account overcharged

I had contract with Telkom mobile for an amount of R369.00 every month. On the 20th December I was debited an amount of R730.50. I received an SMS from telkom saying they will credit back my money as they are aware that my contract has expired and that I should visit the Telkom branch and advise them if I need to upgrade or cancel my contract. I called the call centre on the 18th I contacted the call centre to enquire about the money. I was told they will reverse it and also went to the branch at Kempton Park they also told me it will be reversed. I need a detailed information and as to why was I charged so much and also need my money reversed back to my account.I had contract with Telkom mobile for an amount of R369.00 every month. On the 20th December I was debited an amount of R730.50. I received an SMS from telkom saying they will credit back my money as they are aware that my contract has expired and that I should visit the Telkom branch and advise them if I need to upgrade or cancel my contract. I called the call centre on the 18th and was told it be reversed and also went to telkom branch at Kempton Park also confirmed that it will be reversed. I need my money back.