First Day Frustration

It had to happen sometime, but the first cab ride to the hotel?
When exiting the airport there are somewhere around 15 cab drivers standing around at the exit. I was told to only take an official taxi, and this seemed to be official, all standing around with police nearby, surely not a group destined to rip off their customers.
A gentleman inquired if I needed a taxi, and I said yes, so he led me to, seemingly, his taxi, only... after he loaded the bags in the back, another driver took over. I was alarmed, but not yet ready to bail (a mistake). My new driver and I drove about 5 minutes away and picked up my original driver (confused yet? I was). Then we turned around. The hotel was further away than I had thought (though only 6 miles, it appears the way the roads are structured makes it more like 10), however, the driver took a purposefully long route (skipping his exit the first time, taking a later one, and doubling back). I let it go, since he now outnumbered me, and had complete control. We got to the hotel, where he tried to drop me off with a bit of a walk to the door and charged me 180 euro! I insisted that we go inside first ( so that I would have a witness), only, he duped me. We got inside, and he brought my bag, then he complained that I was not willing to pay the full price. I asked the hotel attendant how much she thought it might be for a cab ride from the airport: "40-50 euro", she said. I agreed, and stepped back out to pay the cabbie (who had exited and was still complaining). I told him that 180 euro was an impossible price, and he fooled me into thinking I had misheard him: "it's only 70 euro", he said.
Relieved, I handed over the money, without thinking to do it back inside in front of the attendant. The cabbie, therefore, pocketed the 50 and pulled out a 10. He said "30 is not enough". Completely baffled, I went back inside to check everything (so as to make sure I had not put my 50 euro in some other place). I had not, of course, but the man continued to complain! The attendant could do nothing, because she had not witnessed the transfer. The cabbie then took a 10 euro off of the desk where I had laid it, while putting the other 10 back in his pocket (he has now taken 80 euro from me). Again he shows 30 euro and says it is not enough. I wouldn't care, knowing full well that he has ripped me off, but he takes one of my bags and starts to leave with it! I take it back from him, but am forced to give him another 20 euro to shut him up! He complains on his way out, too, as if I have cheated him. In summation, the prick ended up with 100 euro of my money, considering the exchange rate at the airport, that totaled $190 for a lousy (and extended to make it longer) 20 minute cab ride. I will not be leaving the hotel the next two days and will only take a cab recommended by my hotel. I should not have come early; this was evidently a huge mistake. It will take some time for Siena to make up for this first day problem.