Wowcher. Apart from having a deeply stupid name, it's the first time in ages I've bought anything online and found an interface so excrementally poor.
We've had a pergola installed in the garden and needed some furniture for it, and Mrs GSV had seen some offers from Wowcher. The discount brought price into line with what you can get from Amazon, and it seemed like it would make better use of the space than anything else we'd found, so we went ahead. Two emails received, one confirming the order, another saying we had a voucher to redeem. Didn't want to buy anything else, so didn't proceed with the latter.
Turns out that if you don't follow a poorly-signposted link to 'redeem-with-us.blah blah', you haven't completed the order, even though they have helped themselves to your cash with unseemly haste. There's no follow-on to tell you that you haven't finished buying, and this link wasn't obvious. We found it all by basically flailing around.
Managed to get it sorted, but I believe my state of mind would have been best described as 'incandescent.'