Unfortunately, as the message itself was a scam your agreement with the "seller" has nothing to do with eBay, and they won't divulge their contact information to you.
As you have been the victim of fraud you need to report this to the police, and get a crime number. (The police may refer the case to action fraud, which deals specifically with online fraud.)
If the police carry out an investigation, they have their own procedures for contacting aBay.
Good luck, but don't build any hopes. This scam is almost certainly the work of professional criminals. Your money could be anywhere by now and it's unlikely that the perpetrators will be easy to trace.
