Logic

So, I ordered a half of a grapefruit along with my bi-weekly milk delivery, and I got a full orange. But upon closer inspection, I realized it was actually a small grapefruit. But not cut in half. So... does the fact that it's still half the size of a regular grapefruit then make it a half? And if I wanted them to cut it for me, should I have been clearer? And since when is a grapefruit as small as an orange? Maybe it's a baby grapefruit. I'm all levels of confused.