is it a scam?

Hi,
I've sent money to book an apartment in London and looking at many posts here, I think I've been scammed...
My contact was www.londonnewyearflats.com (through Craigslist) and here are the bank details he sent me:

BANK NAME: SECURE TRUST BANK PLC
ACCOUNT NAME: R EDWINRAJ
ACCOUNT NO: 00066826
SORT CODE: 23-54-51
IBAN : GB21BARC20078233479536
BIC : BARCGB22
Address: 50 HIGH STREET, EGHAM, SURREY, TW20 9EU.
Bank Address: 46-48 High Street Nth, East Ham, LONDON, E6 2HJ

I've already sent £300 a week ago but the "owner" keeps telling me he didn't receive it (but I've got the proof from my bank that the money was actually transferred...) and he asks me to send another £300 through Western Union... which I won't dof of course!
Does anyone have ever heard of this site (www.londonnewyearflats.com), of this bank account? What can I do in order to get the money back?
Thanks for your help.

Unfortunately, you have been scammed. I didn't research the website, because I didn't have to in this case. It is already listed as a fraudulent website, which means that people are working on taking it down. You can see that on the site's web of trust report:

http://www.mywot.com/en/scorecard/londonnewyearflats.com

If you can post the emails from them here (with headers--just remove your address), they may help to provide additional evidence needed to help get the site taken down so they can't continue to steal money.

Welcome. As Dotti has said, this is definitely a scam and the website is already being worked on by our site kilers. I have also reported the bank account to a contact who works to get them closed. Please do not continue any contact with the scammer.

Unfortunately, there's not really any chance of you getting your money back, but you should report this to your local police and to the IC3 here: Internet Crime Complaint Center.

Please let us know if you have any questions.