I think she exists, been doing some digging and she has a live LinkedIn profile and is registering a company at companies house.
I presume you have her real name as you transferred money to her bank.
You could try a recall of the funds on the basis the advertised services weren't provided, and if they ask which services, say it was an advance for a back massage appointement.
Failing that, the address she used at Companies House may be her home address, (or her accountant's address), so you could trace her that way, or a search on 192.com may reveal her home address if she remains in one place for a while.
I agree, it's the principal rather than the value lost that's important.
Armed with her home address you could always go through the Small Claims Court which would give her a CCJ against her name, not great for starting a new business.