There is simply no part of FedEx customer service that would deal with it, or if there is, it's well hidden. Yes you could probably go to court over this, but this is almost certainly not worth the time and money.
Source: spent countless hours dealing with this problem in 2023.
The real “customer service” department of any corporation is their legal department. Someone will personally look into your case in response to a legal notice, I promise you. And, in the process of determining whether your claim has standing, they’ll ask the people who can actually address it — and boom, your problem will go away.