In my personal experience, highly unusual.
I don't believe they are ripping you off. When they responded, did the response come from Eva? She is the most helpful.
It is not unusual for them to split orders but I don't want to be more specific. If you receive anything, keep the packaging or photos of the outer.
I don' t know what country you are in but yes, mail from their region can be dicey and come in spurts at times. But... others would also be affected, no?
"Just lost or something?" It doesn't sound right. I would push it with Eva if you are comfortable doing so.