[Resolved]  Indigo Airlines — not serving on board meal service

Address:	[email protected], Mumbai City, Maharashtra, 4000097
Website:	booked via: questtotravel.in

I book tickets from bom to ixa via ccu for my aged parents flight 6e-374 (Date: 26.01.2020, seat no. 9e, 9f), with corporate meal option, since journey time was 4 hours approx. I did web checking and verified cpml option one day before travel. One of the ticket was appearing with cpml cptr (Pnr: veesky) while the other cpml (Pnr: pfgirf). As my parents were not familiar with onboard services, i told them specifically what item to tell to flight attendant. My father took a sandwich+tea and my mother took sandwich+paperboat. On board flight attendant served foods to my parents and gone away. After sometimes flight attendant came back and asked 400 bucks from my parents stating one the pnr:pfgirf was not prebooked with food and it was actually for seat no. 9a. My father did not argue and given money.
Please let me know the reason for this inconvenience.
Ps: my parents were occupying seat 9c, 9d instead 9e & 9f due to inconvenience to fellow passenger (One child and mother was given 9c and 9d). However, my parents had shown their boarding passes.