I'm also skeptical about the dead coon story. I can't imagine a coon dying in a pond unless it was pretty sick. Unless it was a pretty small pond, I can't see how it would do a lot of contaminating. Most fish stockers, that I know, keep an awful close watch on their ponds and holding tanks. They seine, sort by size, bag with oxygen, and ship. They usually come out of aerated concrete holding tanks after sorting. I'm inclined to think that the oxygen tank might have been contaminated. However, that doesn't explain why the larger fish were mostly OK and the smaller fish were dead.
Just thinking. It could be that the fish were put into separate holding tanks after being sorted by size. There might be an issue with one or more of the tanks.
I agree with Gator. Call your Credit card company. I doubt that the threat about not selling you any more fish will keep you awake nights.