When is my appointment?

I have a question.  I work in a doctors' office where we see patients every 28 days so that they can get their prescriptions filled within a certain time frame.  This means we see them every four weeks.  When they leave the office after their appointment, we give them a reminder card.  We also make reminder calls the day prior to the appointment, which to me seems silly because I feel that people who have made it this far into adulthood shouldn't need other adults reminding them of their obligations, but I digress.  Anyway, my point here is that these "adults" leave this office after making their own appointment with reminder card in hand.  Several of them also put the appointment into their Smartphone or their appointment book. Herein lies my question:

Why is it that over half of the phone calls I take at work each and every day are from these very same patients who are calling simply to ask, "When is my appointment?"  OK - REALLY? 

And here's the best part!!  After a reminder card, a reminder call, AND their own call to us inquiring about their appointment, several of them FORGET TO SHOW UP!  Of course, for a "no-show" there is a fee, and undoubtedly, when they show up the next time around for their appointment to find they have a fee, they argue with me that they shouldn't have to pay it.  Umm...yeah, I'm afraid you do!

Why does this happen?  It's not like these patients come in once a year and the appointment slipped their mind.  They come every 28 days...it's not rocket science. It should be routine!

There are times, albeit not frequently, that we are simply too busy to make all of the reminder calls, but what puts me completely over the edge is when patients call to ask when their appointment is only to find that they missed it...and then they blame ME for not calling to remind them!  It is all I can do not to ask them who reminded them to get up and go to work today, or who reminded them to meet their friends for drinks last night, or who reminded them to make their car payment. 

I know it may seem like a silly pet peeve, and I realize we've all forgotten an appointment now and again, but the people I'm talking about are the people who blame others for their mistakes and who feel the world owes them something.  I do all I can to help them "remember" their appointment.  All they have to do is show up. 

Or don't.  I just don't care anymore.