A great kit to get on top off red mite and keep it under control.  These are all the products we use here and recommend.
 
Step 1 - Before removing the bedding (you don't want to scatter mites everywhere but need to kill them in situ!) set off the Red Mite and Insect Mini Smoke Bomb.  
 
Step 2 - Soak the inside of the house with the Nettex 750ml Total Mite Kill ensuring all the perches and corners are throughly soaked.
 
Step 3 - Puff the 350g Smite DE powder all around the house taking care to get it into all the cracks and crevices particularly where the hens spend any time (roost bars and nesting boxes).
 
Step 4 - Add the recommended amount from the 250ml Agrivite Oblitermite to the hens water to help repel any mites still in the environment.  This product is totally natural and stimulates the blood to create its own natural toxins as an immune response causing the red mites blood to coagulate.
 
Step 5 - Add the recommend amount from the 250ml Agrivite Mite Rescue Remedy  to the water.  This contains a wide selection of vitamins, chelated trace elements, iron and key minerals. All of these combined are particularly effective at aiding a fast and effective recovery from a red mite attack
 
Repeat steps 1-3 every 6 days until the infestation is under control and then continue to use the Total Mite Kill and Smite powder each time you clean your hens out during warm weather to help prevent re-infestation.