If you donated the money and specified your donation was only to fix the player on the web site and they accepted it, then yes, you have say in how they spend it. You don't have a lot of leverage if they don't spend it on that but you could possibly sue them.

If you donated the money without telling them what they have to spend it on, they can spend it on anything they want.

Good luck finding a lawyer to represent you in this law suit and good luck spending many times your original donation on said lawyer all because you don't like the look of the audio player on the web site.