Air India — Wheelchair service for Elderly passenger

My Grandmother arrived to Delhi from Chicago on flight AI 126 on 10th November 2021. We had booked a business class ticket and wheelchair assistance for her as she is 88 years old. She was provided assistance from plane to the arrival gate and the wheelchair guy said he will get back but she waited for hours at the arrival gate and nobody assisted her. My parents waiting outside the Airport were try to request every possible person from Airport Authority to trying to reach the Air India service team but nobody provided instant help. I was also try to reach their help desk and customer service numbers but all limes were busy and we couldn't reach. Who will take responsibility for this? Even after booking a service when an Elderly passenger has to wait for hours and no help reaches her. The airline needs to take responsibility for their action.
Passenger Name : Harjit Kaur Sodhi
Flight AI 126 - Chicago to New Delhi
Arrival Date - 10th November 2022