1) £60 for a bloody RPi?? There are £30 on Amazon. The full kit is £44 (Pi 3, PSU, case, uSD)
2) Bit of a dick move to the seller, but if you paid via PayPal and open a dispute with them, from past experience they seem to just side with the buyer regardless and will probably refund you.
3) Chasing it with myHerpes would be the best solution for everyone, but they don't exactly have a great rep.