Sorry m'dear but I just found out that the song was written especially for the ad so all our efforts have been for nothing it would seem. However, there may still be hope. The ad agency will probably find out how popular it is and either credit it or release it, so fingers crossed. I know mine will be :)
the singer is called jon darling. it took some digging, but i'm glad to report that he has a very good record on itunes. it's quite different from ther style of the tune on the advert. but he has got a great voice. hope that helps!