Unfortunately it's a sign of the times. Instead of actually putting some effort into creating their own they steal others works. Along with Ebay I would send an email to Paypal. Since they are out of the U.S. it will be hard to get any legal remedies. I'm wondering if the UK has the equivalent of the better business bureau? You can try contacting the attorney general in your state and ask him/her what remedies, if any that you have. If nothing else this might generate some aggravation for this SH*T HEAD!
I wouldn't stop doing what you enjoy. There are a lot of people here who enjoy and appreciate your efforts. I for one am grateful for your time and efforts. I wouldn't have been able to create the pieces I've done without your professional tutorials on GIMP and Inkscape. I hope you will continue to to do the fine work you have been doing on this site.
Thanks!