Air India — Paid seat changed by airline staff

Hi Team,

I had three passages and one infant boarding flight AI0864 on 27th Nov 2022. All the passengers had opted for paid seat and booked in advance. The air India staff changed the seats on purpose saying that those seats are already booked. All the three family members were given different seats. This is pathetic considering you split the entire family with a 2 months child. Not allowing them to sit on the seats which they have paid. I have called their customer support number, they disconnected after checking the details and when finally I got connected they said they cannot do anything in this case and I need to contact the airport authority. I called the number available on Air India website multiple times and no one answered. Please help.