Crap happens like that to every trader, whether new or old. As some of the guys here say -
a) get over it (not nice I know, but it's a fact of life)
b) realise it's going to happen again and again if you use stops out of hours
c) the spread bet firms are financial firms, and ALL financial firms can't be trusted, doesn't matter if their market cap is £1million of £50 billion, they're all snakes at heart, believe me on this point
d) if you do complain, be VERY civil about it, don't get angry or threaten them with the FSA etc as chances are you won't get anything out of them, nice pays dividends in my experiance
e) what happened, happens because you're trading on a price made up on the back of something else, ie someone can always hold a gun at your head, so if you're any good at this game, trade the FTSE future, if you have enough cash that is - these types of games don't happen when the whole market controls the bid/offer
And finally, I know I;ve said it before but it's worth repeating - welcome to the ****ty world of spread betting