I would e-mail the company headquarters and indicate that this has happened frequently. That way the main office can put a 'watch' on the staffs. This sounds like a horrible thing to even think of, but with many costly or restricted medications this is important to do. It can protect you, and also the pharmacy overall from drug abuse [either using or selling the shorted meds] by the pharmacist or a whole slew of possible other issues, such as incorrect prescriptions.
I say this only because I knew of a pharmacist who became addicted and, needless to say it affected their work, not to mention a loss of license.
It's sad that we have to be 'tattle tales' at times, but one mistake...well OK, more than one seems to be signs of a problem. One at your expense!
I must caution tho? Some pharmacies have 'restrictions' in terms of how many 'days' they can dispense a med for [30, 60, 90 days] depending on the med, how the prescription is written and how the insurance company restricts this stuff. It IS one big hassle. Be patient and find out those limits and what you can do. Good luck?
Hope this helps! - j