This actually happened a few days ago, when my doctor increased my prescribed dosages for both my HRT meds.
Since he wrote this one up for refills, I went ahead & had it filled at my local [major chain pharmacy] a mile from the house, as I figured I'd have to deal with them come refill time anyway.
I dropped off the slip and was told it would be fifteen minutes, so I meandered off. Then I was paged over the PA system to come to the drop-off desk. "This won't be good," I thought.
Three people behind the counter questioned that the prescription was right (simultaneously, thankly, or I'd still be there arguing).
I assured them that all was in order, as I'd read it before dropping it off.
Pressing finger down on the word Estrace, I was challenged, "Do you know what this IS?!"
"Yes, I know what it is. It's correct."
Pointing at dosage, "It doesn't even COME in this dosage! You'll have to take [integer] pills every day!"
"Yes, these are the correct medications and dosages."
There appeared to be some dismay, although it appeared that the prescriptions were about to be filled, so I added, "This is why I got it filled in New Orleans last month. And if you think you're confused, just imagine how my boss feels."