While it is a joke, many businesses still follow their complaints very heavily. I’ve personally had issues resolved simply by submitting a complaint there. Not a perfect system but it doesn’t take long to do.

Email them threatening legal action against UPS. Doesn’t matter if you have any intention of hiring a lawyer. That message (and a complaint to the Better Business Bureau) will likely end up in some kind of benefit for you. Sorry this happens. People can be shitty.