The wilted leaves show the roots have ceased functioning. This is usually from one of 2 causes.
Drying a tree out too hard. If the roots get too dry, the root tips will die. Most of the water absorption is at the root tips. Returning to a consistent watering regime will usually "fix" the problem if there are enough live roots to support new leaves. Don't give up, it can take a month or two for a completely defoliated tree to grow new leaves. It is late in the year to for it to grow new leaves. Protect this azalea from temperatures lower than zero C. A hard freeze of tissue that is trying to recover from late August damage could kill the tree completely.
Second option, the tree was kept too wet. If kept too wet a fungal or bacterial infection can get started which kills roots making the tree look like it had dried out too hard. If you think it might have been too wet, cut through a twig or small branch or two. If there are strange purple or brown rings or streaks of color inside, this is a sign of a fungal or bacterial infection that penetrated the azalea's root system. This is usually fatal, no amount of chemicals will fix this. Separate the tree from the rest of your trees, let it approach dry between watering. If it does not grow new leaves within 2 months is deceased. Discard tree and potting media. Clean pot thoroughly before re-using the pot. I suggest wiping the inside of the pot with a household bleach solution before using the pot again.
Alternating too dry with too wet will also set up the tree for fungal and bacterial infections. When dry, root tips dry, then while too wet fungi & or bacteria will ender the tree through dead root tips.
Scenario 3.
Gently lift tree out of pot, if you see white cotton like masses with soft bodied scale insects then your tree is infected with root mealies. These are a species of mealy bud, in the Adelgid family. Put the tree back in the pot, then mix up a bucket of pesticide sufficient to drench the soil with the pesticide. The pesticide must list Adelgids and or Mealy Bugs as target insects. There are both conventional pesticides, such as imidaproclid, that will kill adelgids. There are also organic treatments that may work. I am not familiar with what products are available in Kiev.
Good luck.