WOOO HOOO for Duffy's great results.
She has done so well under the care of you and your vet
which must make you extremely happy.
Sorry to hear that your vet is retiring from his practice but it's good to know that he will be educating so many more.
Hopefully you will be just as happy with the other vet once you get to know him/her.
I'm not surprised that Royal Canin/Medi-Cal won't agree to give you the toxicology report.
So I would record the conversation with the vet when he/she calls.