I highly recommend Provent A Mite, I use it as a preventative whenever cleaning tanks even if the snakes don't have mites. It's highly toxic though so you really have to let the room clear for a while and keep the snake away. And it's veterinary grade stuff too, you can get a bottle for about $25 looks exactly like a spray paint can and it's really worth it. It kills the mites and eggs so it controls every stage of them. Just spray it real well all over the enclosure and decorations (minus the water bowl obviously, take it out) and especially in the creases where the mites hide.
Yea I wouldn't recommend regular pet store stuff like Zoo Med, Jurassi because it just doesn't work... Doesn't penetrate underneath the scales where the mites are and easily rubs or washes off.
I've also heard of using pesticide strips in the enclosure but it just seems unsafe if the snake can come in contact with it.
It's best to use paper towels as bedding at this time because there will be lots of dead mites and it's easiest to clean. You can soak the snakes in a Betadine bath, it won't kill the mites (well it will help to drown them) but the Betadine helps to cleanse the bites on the snake. Unfortunately it's just a vicious cycle, not exactly something that goes away overnight And over a long time if not treated the snake can become very anemic, not to mention an overall weak immunity to everything...
For the quickest recovery of the snake best thing to do is go to the vet and get an Ivormectin shot. It releases into the bloodstream and is lethal to the mites so that when they bite the snake, they die. Usually the vet will recommend a follow-up shot in a week or two just to make sure the snake is cleared. But while the antibiotic is working on the snake the best thing to do is treat the snake's environment. Good luck and hope your snakes get better. If any of this helps I am glad, my personal experience has taught me best