You're lucky thats the first time its happened to you, its happened to me plenty. I'd rather they tell me than leave me hanging for days. Once I got a really rude message from a guy who says "I already have this PS3 game, sell it to someone else." No please, no sorry, nothing. So I searched him on social media and found out he's 13, a private school spoilt little brat who lives in a $3 million house. So I rang his mum while he was at school and told her she should teach her son some manners. She didnt even know he was on ebay. Anyway she made him delete his account. 

Google their address and you'll find it's nearly always the wealthy people that do this!