probably a daft red mite question

Its not a daft question at all. You never get rid of redmite you just have to control it the best you can and the red mite feed on the birds blood at night.

I treat my birds with Ivermec which you can get from your vet and you drop it onto the birds skin at the back of the neck it does help.  I also rub my perches with fresh garlic cloves(they hate garlic......redmite that is!) use red mite powder anything I can really.