OP, you also brought up more information about the feeders, but it was in another thread (from 2017) & belongs here.
The store needs education: if they buy in bulk & then have to partly thaw feeders to separate them, they may be causing spoilage...
I'd for sure (!) let them know you've been having problems!
It would also be a very good idea to offer smaller feeders next time though...and speaking of "next time", once a snake has regurgitated a
meal, you don't want to feed it again too soon. "Too soon" is your normal feeding intervals...you need to wait at least a week or two longer
before you give any food. It's "possible" that nothing was wrong with the feeder or even his cage temps. (though that remains to be seen?)
but once a snake has up-chucked a meal, they REQUIRE extra time to re-establish their digestive enzymes...without that extra time, they
are very likely to regurgitate the next meal...and this can even be fatal after a few times (from dehydration etc) so it's not a suggestion
you should ignore. Please, let this snake rest for not less than 3-4 weeks now, before you offer any food, and only offer smaller, easier to
digest prey, not his normal size meal, at that time.