Clients get three warnings, with the final one saying right in the subject line: FINAL NOTICE.

There's one client who has paid on time perhaps four times in six years (quarterly billing, multiple accounts). They just keep paying the late and reconnection fees...and those seem to be the only things that will get them to act. (Maybe they have trouble getting the money from their clients? I have no idea. They've never said a thing, never responded to the initial emails asking if they needed to change the billing cycles. Nothing, nada, zip.)