Have you given up on this?
In Chris Voss' book about negotiation, Never Split the Difference, he writes about a technique to help get people to respond to e-mails.
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"There’s nothing more irritating than being ignored. Being turned down is bad, but getting no response at all is the pits. It makes you feel invisible, as if you don’t exist. And it’s a waste of your time. We’ve all been through it: You send an email to someone you’re trying to do business with and they ignore you. Then you send a polite follow-up and they stonewall you again. So what do you do?
You provoke a “No” with this one-sentence email.
Have you given up on this project?
The point is that this one-sentence email encapsulates the best of “No”-oriented questions and plays on your counterpart’s natural human aversion to loss. The “No” answer the email demands offers the other party the feeling of safety and the illusion of control while encouraging them to define their position and explain it to you."
-Chris Voss, Never Split the Difference: Negotiating As If Your Life Depended On It
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I've used this technique and variations on the technique to move things along on 1099 stuff.
If you're trying to get a hold of a prime PM who keeps bowing you off, fire off an e-mail that says "It sounds like you don't want to move forward, is that wrong" or "It's looking like this is going to be impossible, is that incorrect?"
While it doesn't work every time, it has a higher than expected success rate. And if the person doesn't respond to THAT e-mail, you just move on.
Try it out the next time you are stuck and trying to move things forward. You'd be surprised how often it gets you unstuck.
Want the full playbook? Check out Going 1099.