Are there prepaid taxi services

There is supposed to be a prepaid taxi counter inside the airport. the board is present. i landed in ahmedabad airport on 23rd july'15 and stood in the Q of the prepaid taxi counter to get a taxi. the guy manning the counter said that there are no taxis. most of the travellers waited for 15-20 minutes. we were directed to go out of airport and look for taxis. a policeman escorted me outside and led me towards a place which had many pvt taxi guys waiting. he signalled something and lot of taxi drivers circled me. i was told to pay INR 500 to reach IIM road. this was more than what fare was mentioned inside the airport at prepaid taxi counter. i realized it is a scam, but since i had no option, i boarded the taxi. I got down at my destination, but had to cross a red signal for which the taxi driver over charged me another 100 Rs. He asked me to pay Rs.600 instead of 500. these ahmedabad taxi drivers are cheats. be ware. Airport authorities to take a note of such incidences and take appropriate action. gives a bad impression and leaves a bitter taste. on my way back i used a ola cab which i booked thru mobile apps. the return fare was Rs.336. what a cheat the airport taxi driver was!