I had a similar experience this week. I got a notice, "Sorry about your late shipment, we realized our error and sent it out today!" I started to reply, but since they already shipped it out I decided not to reply and see if it came. It came yesterday, and now I have two because they screwed up their shipment tracking process. The item was only ~$20.00 including shipping. If it was more I might send it back but me doing that might mix them up even more?
I looked at the reactor. For the price difference they probably should have told you to keep it, if you wanted the larger one? Things get mixed up like this all the time. Sorry you are waiting. It will be good if they get it to you before next Wednesday. Right now I can't tell you what to expect but hopefully they will make it good.
I also screwed up ordering a replacement pump for my calcium reactor, purchased and paid for two day Federal Express shipping late Wednesday night so it would arrive today. Dumb me! They shipped it on Thursday, so two days means they will deliver it before 2000 hours on Monday! I paid $28 instead of using free shipping so it would be here today and I could work on it before my wife comes home from Florida later tonight.
The kicker, I bought two pumps so I would have a back up and when I took the reactor apart to clean it the old one seems to be working fine, starts right up so I put it all back together and now I will have two spares on Monday. Total loss from online purchases close to $200 for both transactions. I had hoped to get some of the junk cleared out of the garage while she's been gone and ended up with more spare stuff to fill up space and that's how these things often seem to turn out. Let us know when/if the new reactor arrives. It's a good one, BTW!