REFUND - FRUSTRATED!!

I contacted Vodacom in regards to continuing with 2 data cards on our contract. I requested the to keep the contracts the same. I then received a bill for nearly R11 000-00. I called customer services enquiring what went wrong and was informed that the 2 contracts was renewed BUT WITH UNLIMITED USAGE. I then requested a copy of the voice recording of which I was then informed that it won't be necessary as they can see they made a mistake and that they will refund our account with the additional charges. In the mean time I am paying my account at a local branch every month and my phones and data cards have been blocked 3 times already. Every time I call the customer services department I receive a new reference number (I have about 8 reference number already) BUT my account is still not credited with the additional charges as I was promised every time I call them. Sometimes they tell me the previous reference has been closed and the complaint is resolved. BUT STILL NO REFUND ON MY ACCOUNT for the incorrect renewal of my 2 data contracts! How many times must I call in and get a different reference number AND still not have my account sorted?