Just a quick freebie...
This works in parking lots where you pay by putting money into a machine (not when you pay a person at the exit)
All you have to do is drive to the exit, press help. Once someone answers, say that you left your ticket in the machine when you paid X amount and that you were distracted by a beggar. By stating that you were distracted by a beggar, you are putting them at fault for lack of security by the payment machine. Then watch as the barrier rises and you are free to drive off into the sunset.
This has never not worked for me. I have used it over 50 times, probably 100 times, at different parkings lots in the UK and Europe.
(I found this method because it actually happened to me, I then tried it again on a separate occasion where I lost my ticket...)
Good luck
