It's a while since I had an overseas delivery but I seem to recall the last time I got stung with a charge it included a £12 handling charge. So SECollector is probably spot on, and the lions share of your £15.77 is that fee, rather than an exorbitant % tax on the value quoted. I also see it as a risk you take - the vast majority of times you get away with it - but when they get you, the onus is on you the buyer to pay it. It's not on to expect the seller to contribute in my view. Hope it ends well for you.