Poor Service Delivery

We have upgraided in the beginning of February 2015. At the store they told us that our contract will only start at the 1st of March 2015 and that we will have no mobile data available. I put my phone on and a lady from Vodacom phoned me, she asked if I want my mobile data activated. I told her no, I don't want it to be activated, I will wait for the first of March for my mobile data to be activated. At the end of February 2015 I received an invoice for mobile data use for the amount of R900. I logged a call and told Vodacom the situation. They said that they will look into it and let me know. The SMS code is S3-8Z62D-DXF8A, which I received on the 6th of March 2015. Today is the 29th and I haven't received a call back, because Vodacom said that they will give me a credit note for the amount. How long do I have to wait to receive a call back????