How would you handle this?

[Gooch]

its their fault, its their mistake. they're assholes for putting the blame on you for not noticing it. they shouldnt put you in a bad position because of their mistake.

i agree with keyser. don't let them turn it around on you. it's their mistake, not yours. how you deal with your money isn't their business. but how they flubbed their money to you is. they should be apologetic, not angry. this is a huge inconveniance to you, not them. zero professionalism and tact from your boss. sounds like a real douchebag company.