Certified GKH Gardening Expert
Spider mites bring about near irreparable damage! Not only do they, seemingly, sap the life out of everlything, they also bring disease and blights.
I'm afraid that you will have to do several things to bring them back to health.
The first things you will need will be: A HANDFUL OF DOLOMITIC LIME
A TABLESPOON OF WETTABLE SULFUR
You may have to find these online, as they may not be as easy to find as here in the US.
Use these together in the soil, and after you see signs of recovery, then feed with a citrus fertilizer.
Here are a few articles that you will find helpful: https://www.gardeningknowhow.com/edible/fruits/citrus/citrus-mite-problems.htm