Your help and advice really needed!

How would you find independent doctors who can make the decision to use your product? My wife is the primary breadwinner for our family and works mostly for commission. She spends hours on hours driving door to door asking, only to learn that the doctor she’s speaking to is unable to make a decision for themselves because they work for a larger company. Her target doctors are family physicians, cardiac, pain management, internal medicine and geriatrics. Any ideas would be greatly appreciated, thank you.