The likelihood that you'd get anything free from Toyota is slim at best. Since you didn't verify what you were ordering and after taking delivery you didn't notice it I think this is going to weigh heavily on your failure to notice it and refuse delivery on the order that was not ordered correctly. At this point I think its a moot point so you're only course of action is to swap or just get an aftermarket locker.
I personally recommend the ARB locker if you can afford it. The one you'll want to get is the RD129 which applies to all 8" ring gear (12 bolt) application. I'm not sure how much it'll set you back but it will set you back a pretty penny.
I'd say depending on what your ultimate goals are I'd hold off on the rear locker until you decide on larger tires/wheels that'll then require regearing (if that's the route you want to take). If and only if you plan to regear, should you do your rear locker at the same time to save a bit of $$ on the labor/installation since they'll be working on the same part.
Bummer on the whole buying experience
Btw, welcome to UltimateYota!