How do i change my username to one that already is being used?

I want to change the username of my page, but what i want is not available. Can I send an request to Facebook asking to change the username inasmuch as my page is verified by the Facebook?

I want to change my username to facebook.com/benitogama
But this is being used as redirectionament by this profile: facebook.com/benito.gama

Please!! Someone can help me? It’s urgent! Thanks!