I would certainly treat with Panacur using the dusting method.
http://www.frogforum.net/care-articl...first-aid.html
Ask him to replace the dead frog, if he won't then reveal his identity here. I would be thankful that any are still alive and buy from Josh's Frogs, Alpha Pro Breeders or Brooklyn Dart frogs from now on. They will deliver 1st rate animals and guarantee them. Every frog I have ever received from Josh has been in excellent condition and as a matter of fact the first frog I ever bought was a yellow Galac that he sold me and he is still going strong and healthy. Stay away from shady dealers on kingsnake and fauna. I'm sorry this happenned to you and I hope people will learn something from it.