Fin whistling results from subtle design flaws or a construction error. Ask your dealer to get a replacement.
If you have to buy a new fin, I would avoid the Drakes. As Franc says, spin out is a problem with the 2008 fins. I have the iS 111 and the 38 fin has major spin out problems. Part of this is rider style, since the fins have a small foil and are designed to be fast for down wind racing. A little too much pressure on the back foot and you are sailing sideways and they are very difficult to pull back in after a spin out. It also spins out over chop.