A similar thing happened to me 2 years ago. I was transferring from domestic to intl (Kingfisher to AF) and KF flt came late from HYD. The lines for the transfer bus was long and hence KF officials told me to take a taxi.

I got into a taxi and it was after midnight, he went into a dark street and immediately two guys got into the taxi and demanded 200. I thought it was 200 rupees but he wanted 200 USD or else (implied threat). Finally I gave him about 50 USD and got out of the taxi and took an autorickshaw to the intl terminal. I had no time to report to the police since I was already late.