Bandit - we had the exact same thing happen to us. Our cabbie was brutal! we were a couple, and I was getting out at one terminal and my partner a later one. I got out and he said "$15" and I said "Oh really? well wait right here because I am going to get a policeman to talk about this."
He got back in his car and drove off WITH MY PARTNER IN THE CAR! She was screaming out the window "heelppppppp"
He drove up to her terminal, opened the trunk and toss her bags out, then he reached in the car and pulled her out, too. She was so scared she fell out on the ground. Then he sped away.
Always make sure they turn on the meter as soon as they start driving. If they don't tell them you know the usual price from the Port to FLL is no more than $8.