iMessage issue

Bought a MacBook Pro Retina 2 days ago, but I was disappointed to find an issue with iMessage activation that persisted for 2 days, 2 days of apple support (first chat then call) with all attempts to fix it failing, I booked an Apple Genius Bar appointment. They said the device had to be faulty and they're gonna replace it, however I made sure that I would get my replacement the same day when I booked the appointment since I have urgent college work to do. Alas, I returned the faulty one but I didn't get the new one and I have to wait another day to get it even though I booked this time slot knowing I would get my device the same day.

This is my first MacBook but I am an 8 Apple user, this is not the quality and convenience of service I expected from Apple.