this is very old trick....
They did the same trick with my dad many times...
When you stop your car for re-fill... They'll keep you busy in talking rubbish.. (like their new schemes, or any pumflit etc).
So that you loose your attenntention towards meter.. Please note .. most of the time it says 200 or some small amount..
If you don't notice it they'll start filling it immidiately and then ask for the amount.. OR they ask the amount very first time and then keep your attenntention towards different things.
So if meter says 500.. actually its 200 or 300.. But they oftenly do that when you ask for Full tank.
I caught them red handed.. (shall patrol pump faisal town).
I stopped my car and opened the tank from inside. Immidiately 3 people came to me and tried to keep me busy in their nonsense talking. I immidiately turn back and ask the person to clear the meter first before filling the fuel. So he did that, and after that those guyz went back without talking to me and then I asked them to come and continue what they were about to talk... I laughed on them and gave them real hard time in front of everyone arround and few other people also jumped into discussion and appriciated me...