How big are the holes? Quite important for ident of problem, and it doesn't sound good. Worthy

When Pecans in this area get that problem, we treat the roots with imidacloprid--not sure which brand is available in India--and don't eat the nuts for a year. As far as I know, that's the only way to kill the borers within the tree. After that year, we spray the trunk and branches every spring with permethrin, to kill the adults as they land and lay eggs. It's possible that neem oil or cedar oil will work for the latter purpose, to confuse and repel the adults. Time of application is important, and may be different in your area, or for the species you are dealing with.