if you have their number, call them back and verify, you have nothing to lose and it's not against the law to verify a call...did you fill up any raffle ticket from the last six months to any shops or supermarkets? who knows maybe you got lucky!!...but if they ask you to send money thru western union to claim your prize or solicit a thing using the cover that you won this and that..then forget about it...
a friend of mine won a car from qatar shopping complex raffle draw but what he got at first is just a call and info that he won..he was asked to call for verification.
take the shot..you have nothing to lose!!! and congrats if it is legit!!!