Well i downloaded the whole OST and PLUS OST. The name of Kuja music are Kuja's Theme, Dark Messenger, The Origin of Kuja and Kuja Leaving Burmercia.

The list is also on gamefaqs.com and at http://store.yahoo.com/animenation/sscx-10043.html
I dunno where you bought your cd but there is no "Wicked Melody".