This sounds about like my experience with Basil. Try and find ANY reason that the problem MIGHT be customer related and avoid doing the warranty work.
So because a customer gets a flat and puts a spare on, that gives you the right to jump to the conclusion that they drifted into a curb and broke the diff? Are you kidding me?
Like I said before, my experiences with my Ranger were enough that I’ll never go back to Basil, and anyone reading this thread should do the same.
And by the way, diffs do fail catastrophically under normal use some times. The rear diff in my Expedition was starting to chatter real bad, and after changing fluids it didn’t get any better. I took it to a trusted mechanic (read NOT BASIL) and they tore it apart, only to find sheared pins and a complete mess. The guy basically had to invent a tool to get the axle out of the diff. I’ve never hit anything, and I’ve only done light towing (light compared to what the truck is rated for anyway).