these mites are terrible, my birds haven't had this type, but I've encountered other types(through no fault of my own) and they are buggers.
you need to do the ENTIRE cage, cracks, inside and out, remove the tray, clean it all.
even underneath the cage, remove any labels from the bottom of the cage as well.
remove ALL toys, swings, etc....and buy new, or if you have brand new ones he's never used, only put in one perch, and a swing. leave everything else out, until he's fully recovered.
change them everyday, disinfect them, until the treatment is done
No point in putting back the old toys unless you are absolutely certain they have all been killed or you will re-infect him.remember to do the ends of the perches as well
Ivermectin in your best choice for treating him, they will be dead in 24 hours.
as for treatment of the cage, A.I. L (avian insect liquid) is your best choice, readily available in the states, but banned in Canada.It comes in a spray and can be used to treat all toys, perches, and cages....it's excellent and very effective
remember to treat your spare cage as well, perches everything.
Use different seed cups daily.
good luck