False adverti*****t on special prices

[URL Removed] Online bookings falsely advertised a special price on a flight that I booked this week. After I placed the booking (2 seats left) to Durban and return flight (2 seats left) back to Jhb and paid for it , all online, I received a phone call saying that the return flight unfortunately has no seats left at the time of my booking and they need to contact the bank to find out if the moneyis in their bank of has been returned to me. I was pretty upset but they promised to call me back. They said the outgoing flight was ok but I could get another return flight but at a higher rate. i waited and the call never came. I called their office yesterday, they couldnt help me and said I had to wait for the Head Office to call me back. This morning I called and I was told that the special that I booked was no longer valid, even though it was included in the available flights and price choices. They will refund me back my money. MY QUESTION - HOW CAN THEY BE ALLOWED TO FALSELY ADVERTISE A PRICE, GET A PAID BOOKING, AND THEN TURN AROUND AND SAY IT WAS A MISTAKE?