This may seem counterintuitive, but your emails are more likely to be read by the recipient if you talk to them on the phone. These media contacts get scores if not hundreds of email pitches a day. They also have other responsibilities besides reading emails and booking guests. So it is understandable that they are not going to necessarily read the pitch you worked so hard to craft and send their way.
But if you get them on the phone, they are likely to read the emails. Here's what happened with the Yahoo Finance interview as an example.
I got the contact on the phone and said I had been sending her emails in recent weeks. She did a search and all of my emails came up. As I was reiterating what was in the emails, she was reading them. As you might guess, what I was telling her on the phone about Eric's credentials and abilities as a subject matter expert had greater legitimacy because she saw all of the correspondence I had sent over the previous weeks that indicated just that. If I hadn't called her, she might not have read any of the emails, or at the very least, she likely wouldn't have responded to them by booking him as a guest.