I booked an apartment in Los Cristianos in Tenerife. The website clearly stated that it would cost £687.00. I was charged £708.72. While this is only £21.72 over, if they do this to all their clients they are making plenty of money by overcharging. I complained to booking.com by e-mail twice, leaving a week between each e-mail. I received no reply. I telephoned, and the person who answered claimed that the price was in Euros. In fact it clearly stated the price in pounds on the website when I booked, with the euro price (809.80) in small numbers next to it. In any case, if the price in pounds was converted from euros there is no reason why that conversion should be any different when charged to my card immediately afterwards. Beware! There are plenty of other holiday booking sites.