I found this to be a common problem with frilled dragons. The mites hide in the neck area thats covered by the animals flap of skin and so they arn't visible unless you make it mad. When i voulenteered at a pet store, we go our animals in from some horrible distributor, reason being, he was "cheap". The owner sold the Firlled dragons without even once looking at them.
For your situation, I blame the owner. He is not responcible enough to buy from a reputable breeder and mites is one of the problems you have encountered. Who knows what else is wrnog with them on the inside.
Recently bought a frill dragon from my neighbrough hood pet store. When i noticed he has mites. i went back to the store to ask for help. but the manage was not in. the girl told me the other one they had has mites two. they got them from the bedding being unclean she said.So i went back the next day to see the mangager. He told me it was my fault. he had no medication for me. Refered me to another store to buy medication. he was very unhelpful. But he did give me a free bag of forest bark.Which was not big enough to cover half of my cage. And at the same time my bearded dragon cage became infected with mites.Is this something comman. or am just lucky.I have been keeping bearded dragons for 6 years know with out any thing like this before.
Many times a cage clean up and a warm bath to the animal is all it takes
