I did it twice in about four weeks. Gawd knows where my mind was. The first time I took it to a garage and they sorted it out; it cost me about £60 (this was a few years ago), and then I remember being narked that I then had to go to the garage to pay for the correct fuel.
And about a month later, I did the same again, but this time I had my car home and I fashioned out a little hand pump from a huge water pistol (piston type) and managed to drain the tank that way; though it took about an hour and I was stinking of petrol.
And then, the kick in the nuts, I went back to the garage to pay for the correct fuel.