Gumtree ad: use ebay fake account for money transfer

i saw the car on Gumtree ad last week friday. i try to contact the phone number that shown on the ad: phone is ringing but noone pickup. next day on saturday they contact me via email. they said they gonna posted on ebay within 2,3 day to get paid from as they said it's secure and have ebay protection. when i check on the link that they sent me everything look exactly the same like ebay. so i believe to them and i transfer 4800 pound through ebay financial agent by my debit card. after payment nothing respond till now. my life was destroyed and i'm so devastated. now this ad appear on gumtree again. please give me any suggestion that how to track down and take legal action on whoever behind this ad. thank you. pls give me advice that how to get money back.

Name Evelyn Hudson
Bank: Barclays
sort code : 20-98-21
account number 63182509
Reference Case ID E57812

Address: 21,Stirling Street,
Dundee, DD3 6PH
United Kingdom

Phone number 07870279529
077741235623

exactly the same car that show on the following link
http://www.gumtree.com/p/cars-vans-moto ... to-content

Please Helpppp!!!!!
San


Bank acc. reported - CW