Money disappeared from my account!

I had a Balance of R550 in my account for a while now. Last week week Upon trying to use it, I noticed my account is on a zero balance. <br> How is that possible? Surely my funds cannot expire!!!!<br> I sent a mail enquiry last week, up till now no response. <br> This is *****! <br> I want a full refund into my bank account immediately!