Every pitch should have dual goals:
1. Ideally, you'd like to get covered.
2. Absent that, you'd like to increase the likelihood of getting covered in the future.
So you should think of your pitch as being more about making your company look worth writing about. In particular, don't breathlessly oversell a minor piece of news.
If you're a native English speaker, you should strongly consider going without a PR firm altogether. They're the sort of outfit who follow the cookie-cutter advice in the post linked here and think they're adding value. They also are very bad, with few exceptions, at finding credible ways to make you sound unique.
(First time I've posted a link to Hacker News. I'm curious to see what happens ...)