I got some Ivermectin online for Yuna when she had that bump on her head, and remember when she blew her coat? The vet did all sorts of tests (and never got any results of what her problem actually was). I got the ivermectin and gave her one does of it- if it was anything mite/flea/whatever related. It seemed to help. I would suggest getting it online to save a ton of $$$ though. Don't get it from your vet.
I of course discussed giving this to her with my mobile vet (who was not the one I took her to for the tests) and he agreed 1 dose would probably clear whatever it was.
With that being said.....No I have never had mange here so I don't know how long ect. so I cannot help with that one. But I am sure others can!