It’s a familiar experience for many people who take prescription drugs: Your doctor prescribes you a new medicine, or you try to refill an existing prescription, but, for some reason, you can’t get it.

Companies known as pharmacy benefit managers, or P.B.M.s, are at the center of a system that can make it extraordinarily difficult to get your medication. Most Americans rely on one of the three biggest P.B.M.s: CVS Caremark, Express Scripts or Optum Rx. These companies are hired by your employer or your health insurer to manage your prescription drugs.

We’re reporters at The New York Times who cover the business of health care. We just published an article explaining how P.B.M.s work, and we’re continuing to report on this subject.

We want to hear about your experiences — positive or negative — with these companies. Maybe they put up roadblocks that made it hard for you to get your medication. Or maybe you enjoyed a seamless experience.

We read every questionnaire response, then reach out to a portion of respondents from whom we’d like to learn more. We will not publish any part of your response without talking with you further. We don’t share your contact information outside the Times newsroom, and we use it only to contact you.