40 % burns is quite a big area and period from Nov to March is long enough to heal. Wounds from burns usually take long to heal, the way you are narrating it appears as if strictures are also formed. Surgery can be considered.
In ayurveda we use aloe
gel for local application, it is known to heal burn injuries rapidly, as this is gel in natural form so it will soothe the skin and also prevent discoloration. Internally use some blood purifiers as haridra and mahamanjishtha and also add immuno boosters like aamla to her diet.