Another aircraft was provided to take the passengers to Kolkata.

A Kolkata-bound Air India Express flight returned to Bengaluru on Sunday evening due to a technical problem.
Flight IX2718, operated with an Airbus A320, turned back after remaining airborne for more than two hours, according to data from the flight-tracking portal Flightradar24.com.
“One of our flights from Bengaluru returned to the airport following a technical issue. The aircraft circled to burn fuel and reduce weight before making a safe, precautionary landing,” an Air India Express spokesperson said in a statement on Monday.
A replacement aircraft was arranged to transport the passengers to Kolkata.
The airline has initiated an investigation into the technical snag.