I can't speak for other Petsmart vets (Banfield) but I did have a very good experience with one local to me. They had one vet that dealt with "exotics". I found her after my female beardie completely chewed up/mangled my male beardie's tail (they are a mated pair). I knew of other vets but this was on a Sunday. It turned out she worked only on Mondays and every other Sunday-I was super lucky. It was a very serious injury and he ended up losing about an inch of his tail but this vet was awesome and he is doing great now!!
I hope your snake is okay!! :)