Online price change

I cant believe what happened today. This morning (18/11/15) at about 10:00 I searched Hi-fi's website for cellphones. I saw the Samsung J1 for R1000. So I went to the store to go and buy it there instead of buying online. When I got to the store (Westgate), the manager explained to me that I have to order it online (choose the click and collect option), then come back. I went home to do as he said. Suddenly (same day, at 13:00) the price has changed from R1000 to R1549. How is this possible???? I immediately phoned ***to lodge a complaint, but I decided to write it here as well. I am still waiting for the reference which were supposed to be sent via sms. I was told that someone will contact me within 24 hours. So now I am waiting for the call ...