You might want to try black knight, I know it kills mites.... I think it might work on ticks too... Be sure to make sure to get ALL of the ticks and mites with it though, I would soak the snake for at least 30 minutes before spraying... Maybe use a towel for bedding to see if there are anymore.. That's what I did with my burm, it had mites as a baby, I bought black knight, it got rid of them until I changed beddings (which I will never leave newspaper and paper towels) BUT With paper towels the mites and ticks are black so they will show up on the white towel... But I would spray the cage with it, the snake with it... probably 3 times within a week (VERY Seperated dates of course)... This is what has worked for me twice with mites.... Black knight should work with ticks too... And be sure to check the head too!!!!! But GOOD LUCK... this crap is the most frustrating stuff in the world....
Best of luck,
-Ben