Bert, there have been some good suggestions. Some I will parrot. You do need to have a consistent policy that you apply to everybody. Now, everybody already freaking KNOWS that they are to pay you, but they just feel they can "get away without paying you." You also need to have billed a patient 3 times with 30 days between billings before sending them to collections. For larger balances, collections will work. I've done it.
I suggest reviewing your records on each one to see how many times they have been billed. Then resume the 3 billing notices system which is rather standard. If someone has already been billed 3 times, send them a nice letter stating that if they do not pay their bill within 30 days they will be sent to collections. If they have a larger balance ($200 or more), offer to arrange a payment plan of $50 per month to be automatically billed to their credit card. Anyone who balks at this should be dismissed.
Announce a new policy that all patients (or their gaurdians) must leave a credit/debit card on file pre-authorizing you to charge future outstanding balances to it. Put a cap on a single charge ($135 is a good one). Higher amounts can be given a payment plan that will automatically charge to their credit/debit card. Have a document outlining how this works and have them sign it. It should contain the last four digits of the card and the expiration date.
Updox has a facility whereby you can store credit card numbers and charge the card. Credit card numbers are stored by a company specializing in this named Braintree. This was the single best thing I did to stop our growth in accounts receivable. It was like it hit a brick wall. Yes, Alice is uncomfortable confronting patients about their bill, but she is getting better at it. But primarily I do it.With her its only when they think they can "go over my head." They don't realize that i'm really her business partner, and we separate duties to basically she's in charge of medical issues (I can't do that) and I do ..well..everything else.
I agree with you about the bell curve of patients. No, you should not bring this up in the room. In fact, you should separate yourself from it as much as possible. We too have patients we would hate to lose, and some we lost. Others left and came back. After awhile you end up with patients who actually respect you and your service, not just pretend that they do.