This is not unlike a developer building a house and hiring a subcontractor to put in the plumbing. The plumber does not deal with you, the buyer, and does not owe you anything: he owes good work to the developer who hired him.
I hope you can see that your anger is misplaced: USP owes you nothing becasue you never actually asked them to do anything. In fact, they were nice to have caught your mistake.
Note also that your post says not a word about owning up to making a mistake. I know, it's frustrating, but wasn't it your mistake to begin with?