[Resolved]  Indigo Airlines — harassment at the check in counter

Address: Mumbai City, Maharashtra, 400078

Our ticket from mumbai to dubai was booked by travel agent. Few days before travel we changed the return date and paid in dhrams by credit card. At mumbai airport check in counter we were held and asked to produce the card from where the payment is done. We thought they are asking to show the main ticket payment proof but the main ticket money was paid by travel agent directly to airline hence there was no card involved. Then they asked as to pay full ticket money. Then we showed the card from where we paid 90 dhs to change the date and that’s how they allowed us to board the flight.
My question is
1) why don’t their system at the airport showed the payment done for the ticket and only date change was done by card?
2) who is responsible for the trauma that the 80 year old senior citizen went thru?
3) what action can be taken for this unpleasant experience of indigo airlines ground staff?
4) why the ground staff not well trained to handle these situations wisely?
5) need the strict action against this unprofessional and inhuman treatment to the old lady.