I got shorted on a controlled substance I take and anyone knows if you don't get the proper dosage of that, those withdrawals can have dangerous effects. Here's how I mitigated that risk. Also, this will do for any pharmacy.
I bought myself a pill counter container 3 years ago after the incident and my doctor being kind enough to write me another prescription and trust me. I count my pills into that container everytime I get that particular medication.
3 years later, I've only been shorted once and I caught them on it right away. They were courteous, admitted their mistake and gave me the proper amount.
Moral of the story is treat your medications like your money. I know I don't ever leave the bank or ATM without counting my money. I also do not leave a pharmacy without counting my pills either and you shouldn't.