I recently bought a Vortex Sparc red dot for my AR and got the shipment in two days ago. It came with various different mounts, two batteries, and a lifetime warranty. Haven't had a chance to test it out yet but I can tell I'm going to love it.
Anyways, missing in my box was the 2x magnifier that was supposed to come with it. I emailed Vortex yesterday and within an hour or two they responded telling me they were sorry and would have one shipped out immediately.
Always love a company who treats their customers well. I highly recommend using Vortex.