@amolraut, congrats for the Linea. Wish you a great ride and ownership experience. The places where you have shown rusting are very common in Linea after 3-4 years. I have seen too many Lineas, Puntos developing rust at the same place. Perhaps Mumbai's coastal air & rains are responsible for this. But you must get this fixed as soon as possible. If painting is not an option, try getting the window weather seals replaced and channels below cleaned and filled in with some rust-proofing solution or welds and later body filler etc. Any good body-shop will help you with the same. Also a touch-up with black paint will be nice. A complete overcoat will keep the car from further rusting. This you should do as priority because rusting is too bad for any car and needs immediate measures like pest control for eg. to stop spreading in whole car. Additionally try 3M or Dinitrol rust-proofing for whole car including doors and underbody, but that is after fixing rusted areas with welds, sanding, and/or body fillers etc.