Business advice
Today I had the dubiously satisifying experience of catching one of our vendors telling an outright lie. I even told the vendor that their story did not match my understanding, that I would independently verify their claims, and that maybe I had misunderstood what they were saying and I'd be happy for them to clarify. Sure enough, they repeated the same position.

I tried to give them a way out, I really did. Now they're going to need to find some way to either escalate matters further, or retreat without losing too much face.

Here's some advice if you're in business, or looking to go into business. Everyone makes mistakes, and it's okay to admit that you're wrong. If you are so ethically bankrupt that you're going to tell a lie to try and cover bogus charges, then at least tell one that the other party can't easily disprove.

Our vendor is either ignorant, stupid, or immoral. All are good reasons to cease doing business with them.