I thought it would be useful if I copied you with my post from another forum.

Having spent over half an hour checking availability/schedules / pricing and then completing the long booking process it was rejected after credit card input with the message “booking not completed, rejected by web browser”

I then phoned their UK freephone number which eventually was answered by their India call centre
I explained the problem and they said they would take a telephone booking.
Long conversation, poor line and lots of phonetic spelling eventually got to the credit card input.
Result-booking failed.
I suggested a different card but was then told that their Indian Bank did not accept Mastercard or Visa from non Indian residents, only American Express and they will not take debit cards.

Why didn’t you tell me this before I started, I politely asked through gritted teeth?!

I checked with my card providers to check the amounts had not gone through or had been rejected but was told there was no activity and they had probably been blocked by the Indian Bank, a common occurrence.

So I tried to book the internal Kingfisher flights through my usual sites.
Netflights and Expedia couldn’t or wouldn’t quote although the former said if we booked our International flights they could do them as an add on.

Anyway – ebookers came up trumps, flights available on line at only £5 more for DEL/SLA return than if I had been able to book direct with Kingfisher.