If they didn't have enough for your complete prescription, you should have been told so you could go elsewhere if you chose to.
The fact that they gave you a single unwrapped pen means that they are opening batches and dispensing them singly. Sorry, but with all the posters about how to dispose responsibly of your sharps etc., I think it's time your pharmacy acted responsibly and stopped opening batches of pens and handing them out singly.
It's very difficult if you need that medication, to refuse the single pen to keep you going, but you really shouldn't be put in that position. If something had been wrong with the pen, the whole responsibility would be placed on yourself ... because you accepted it, not on the pharmacy for offering it.
I wouldn't use that pharmacy again.
I sometimes have used a nearby pharmacy to get my meds and I'm horrifed at the counter staff's lack of basic education never mind medical education. My surname name begins with F and 3 times I've stood and watched the girls in white uniforms and intellectual specs, intelligently looking through the box marked G only to come back and tell me, not that they couldn't find my prescription, but that it simply wasn't ready. Twice I stood there and told the girl my name and watched her yet again go back to the box marked with a G to look for a surname beginning with F. The final time I had to write the letter F on a piece of paper and point to the damned box myself! :shock:
Needless to say I now go to ASDA or TESCO because the staff seem to have their wits about them in the large supermarket pharmacies.