The way I treated for mites in the past is this: Throw away all substrate in the cage. Clean out the cage and dry it. Spray PAM in the cage including all corners. Let the PAM dry. Use white paper towels for now instead of shredded bedding. Put down the paper towels and put your water bowl back in, then the snake. You should be able to see all the dead mites on the white paper towels. After a few weeks of using the paper towels, if you no longer see dead mites, you can switch back to your usual bedding. Do this to all the snakes in your collection. Pretreat every enclosure that you put a new snake in and keep it on paper towels until it has finished its quarantine period. If you follow this procedure you should not get snake mites in your established collection again.