eDreams online booking for flights not trustworthy.

I went online to make a booking via eDreams. I tried twice and it said something went wrong before I can confirm the booking. Then I get a message saying that my flight has been confirmed. The cost was just over R1200 for 2 flight tickets but I was charged just over R1700. I called the call centre and explained that firstly, it did not go through because the website said something went wrong. When asked why the extra R500 and some odd, I was told that is because I chose the cancellation option which I did not choose. They refuse to refund my money. I am very unhappy with the way eDreams has handled this whole situation as I am 100% sure that the amount showing was just over R1200 without an option to cancel the flight. I will never book with eDreams again. A friend of mine had a very similar experience.