In answer to all the above posts: If you look back over the last 7 years you will find similar posts about CMC (Deal4Free). Many users nicknamed them STEAL4Free.
When they opened for trading in Australia a few years ago, Forums were inundated with complaints from traders who were amazed by the antics of CMC. Their posts may still be on Incrediblecharts.com.
They say they hedge your bets, so it doesn't matter to them whether you win or lose. This is rubbish, borne out by their requoting, delaying trades etc. A trick they use is to allow you to open a trade at the screen price and confirm it at a different price - which is always against you! When you phone them to query it, they will tell you you are mistaken or that the price changed at the very second you opened the trade. DO NOT ACCEPT THIS. Tell them you record the screen in real time and have proof of the trade price. They will back down!
PS. download (from the web) a screen capture program that has video capture, and turn it on a few seconds before you click to trade. Then you WILL have the proof if they persist.
IMPORTANT - If you trade with them, buy a cheap telephone recorder from Maplins and use it whenever you phone them. They can't deny a trade, or it's price later, which they have done to me on numbers of occassions. I closed my account with them because I felt I was dealing with a bunch of East End wide boys - well, thats how they talk, trade and treat you with contempt.
Pete