This is probably the source of the confusion! Thanks for the helpful reply
You actually made me chuckle with the mcg/μg thing. Last year, my pain management doctor wrote me a prescription for '50mcg Transdermal Fentanyl Patches' and the dippy woman at the pharmacy told me that they 'didn't stock that strength' and only had them in (as she said aloud) 'fifty yew-geez'.
Knowing what she meant, I was like 'Yeah that's what I'm after - 50mcg'. After a brief period of frustration she eventually showed me the box that had '50μg' written on it and stated that she couldn't dispense my prescription because it said mcg. Fortunately she was only an assistant at the pharmacy and not an actual pharmacist. She was pretty embarrassed when the pharmacist explained what 'μg' was, and then apologised profusely.
An honest mistake, but yes... The use of μg can be irritating!