Tell the PM to copy and paste your instructions in an email to them since they're not responding to you?

You could also ask the powers that be that you be given direct reporting responsibility. if escalating doesn't help then something else you could try would be to create a dashboard that tracks your requests and their responsiveness on an ongoing basis and report that to them and your management chain.

If there are expectations of you that you are not setup to deliver, your management needs to know that and manage it on their end and the best thing you could do is provide weekly examples of something that needs help.