Bombay Hospital — charged surcharge @ 20%

Address:

Mumbai City, Maharashtra, 400068

My wife was hospitalized on 3rd march 2018 and discharged on 4th march 2018. Hospital charged 20% surcharge on bill which was not intimated to us during admission.
Are 20% surcharge justifiable?
The hospital bill was covered under medi-claim but surcharge was not paid by insurance company.

Its like some hotels are charging service charges on bill and which are illegal as per government.