You might want to try soaking a cotton ball in olive oil then swabbing your cats ears, especially over the area you are seeing the mites. The olive oil will suffocate the mites. Leave your cat alone for about an hour then take another cotton ball and soak in rubbing alcohol and clean the ears again. Repeat this again after a couple of days. I use this remedy on my cats ears and it seems to keep them clean and mite free. You might want to consider getting a second cat, they enjoy keeping each other groomed and clean areas that is hard for them to reach.