Get Callingtons Snake Mite Spray, I used this when my bearded dragons had a major infestation of red mites. Make sure you are using newspaper substrate or something similar, and change every couple of days. Spray the whole enclosure with the snake in it, close the enclosure doors and leave it to fumigate. No need to remove any reptiles just spray the enclosures with a basic substrate in to prevent any mites from burrowing and hiding etc. Also remove any wooden furniture and either bake them or bin them! Do this for all enclosures, also spray the room. Carpets etc. Repeat in 7 days to ensure all eggs have been killed. You may still see mites that are a bit darker on the snake. These will be dead and will come off with the snakes next shed. I was contemplating using predatory mites but callingtons worked perfectly and i always keep a can spare.
I remember using this and put locusts in my enclosure a few days after spraying and they were vomiting everywhere and even they died! It will definitely destroy the mites!