I feel your pain - we've had an unseasonably warm and dry winter, followed by a very warm spring - perfect conditions for the mites and man are they relentless. My mite population exploded a couple of months ago so I did the following:
Evict my birds from their coop to a spare pen or cages, completely empty the coop of all bedding, spray a literal TON of Ripcord spray (I take NO prisoners with this stuff). Active ingredient is alpha-cypermethrin in the form of a suspension concentrate. You guys will have different brands available but I find this stuff will NUKE everything so cannot recommend it enough. You need to leave the coop to dry thoroughly before refilling with bedding and allowing birds back in.
Then for maintenance I have a chicken specific concentrate that is designed for mites and coop cleaning which is safe for spraying without evicting your chickens. I do the perches and nooks and crannies every week or two depending on the weather.
For the birds themselves I maintain a regular regime of Ivermectin Pouron and ensure they have outside areas to dust themselves (mine prefer just plain old dirt holes LOL).
Thereafter you just have to keep up your regimens because if you lapse for even a small period the little boogers will get going again.
Wishing you the best of luck!!