Beceee, the best treatment for mites is Avimec or Ivemectin. It can be bought from vets, or pet stores or online. It is a one drop treatment that needs to be placed on the back of the bird. If it is a severe case you will need to do follow up treatments. You also need to thoroughly clean and disinfect all perches, and virtually the aviary. the eggs will be present otherwise and reinfect them.
I hope you can catch them all and separate them. The Vaseline and oil are work by smothering the mites this is not 100% positive and is used as an emergency or secondary method.