Well, there is. I found out about it the hard way. I've maybe have mentioned this elsewhere but I sold an electronic circuit. It was bought within the hour and buyer duly paid. Seven hours later, he emailed me to say that he'd 'changed his mind' and could I refund him. Initially, I refused, as a deal is a deal in my books on ebay. He got shirty with me, saying he'd send the kit back if I posted it.
Lomg Long story short, it seems that buyers can request a refund through change of mind on Ebay. He eventually got his refund.