I remember that my grandmother used cloves of garlic as repellent to protect the chickpeas against the weevil. Despite the weevil is an insect, not a mite, I have used garlic in the hives against the varroa, and I have read that is used in any countries like Slovaquia, but I have seem that garlic is not very useful against varroa.

I am still looking for a "magic bullet" against that little monster called varroa. You can read a list of miticide plants, but I think that most of them are repellent, not miticide at all.
On the other hand, it is really sad to "kill" the varroa with " borago water" while you are seeing that the varroa is killing your hive.
 Knautia arvensis (escabiosa).
 Chrysanthemum cinariaefolium (piretro).
 Tanacetum vulgare (tanaceto).
 Ruta graveolens (ruda).
 Phumbago europaea (belesa).
 Scrofularia canina.
 Inula viscosa (olivarda).
 Equisetum arvense (cola de caballo).
 Urtica dioica o urens (ortiga).
 Delphinium staphisagria (hierba piojera).

Have you considered moving your bees on to small cell foundation? The smaller cells cause smaller bees, which make it harder for the mites to survive. This system is not a quick fix but a longterm management system that works well for many people. Run a search on 'small cell beekeeping' to find more information.

Try this: To 16 ounces of 1:1 sugar water add 2 cc's of wintergreen oil. Run it through a blender until milky. Mist this on each frame of bees in the hive with a spray bottle. Do it again about a week later. It workes for me.