Billing issues

I cancelled one of my Rain SIM's at the beginning of June, the SIM was not used for the whole month and I was under the impression that you pay as you use. I got a surprise at month-end when I was billed the full amount. I then sent a request to Rain for the money to be reversed and got a reply with a reference number *** that a consultant would contact me within 48 hours. Until now, I did not receive any feedback on my query. By when can I expect someone to contact me?