Did you try penetrating oil? It's not the same as lubricating oil. Penetrating oil can free up jammed, oxidized and corroded bits and pieces.
Or, if they sent you a new lock, just cut the one that's jammed. A hacksaw is probably the cheapest.
Or check the Lock Picking Lawyer channel on YouTube, and other videos for defeating locks. You might pick up some tips on non-destructively removing the lock.