I had to pay a huge bill to call London and cancel my tickets. Most of that was due to the very long wait time. Then they charged me $95 to cancel even though I canceled within 15 hours of booking them. I will not be using them again.
Tip for consumers: Don't expect a full refund even if you cancel within 24 hours of booking. Don't attempt to contact them unless you live in England and it isn't a long distance call.