I did book with expedia.co.uk, expedia.ie and expedia.com in the past and every single time the final amount was taken by the airline (while the expedia pending payment amount never went through and expired after a week or so). This was quite frustrating, but it simply wasn't possible to book the routing I wanted with the airline directly, so in the end I was fine with it. But I wonder, why in tangoll's case, the amount was taken by expedia..
And finally, to share my bit of a story: should have flown on BA metal back at the end of March from EU to US, obviously cancelled by airline. Ticketed by Iberia, bought on expedia.ie. Called right after cancellation, refund promised within (up to) 30 days, and also promise of "refund confirmation email". None of which came. Called again two weeks after, same promises yet again. Now it has been over 80 days and no money, no email. So, I am considering contacting the bank and filing a charge-back.