Unfortunately, we cannot force the contest holder to award you the prize. It is their contest and they can change their mind at any time in the 15 business days after the Final round ends.
During that time, they might ask colleagues for their opinions, show the sounds to their clients, and so on.
Do not take any promises made by contest holders too seriously. And do not take the fact that they wound up picking a different winner too personally. We have plenty of other contests for you to enter.