I had several bad experiences with shell shaukat ali road (near shauq chowk). A person tries to distract you and as you're distracted, the other person quickly resets the meter or moves it to last reading. Beware of that pump. They normally reset the meter immediately after filling.
Another bad was at PSO Iqbal Town where the guy filling the tank asked for tissue to clean the surface of filling area, as I provided him with the tissue, the meter suddenly jumped 200 rupees (hardly in 2 seconds).
Solution: come out of the car and keep your eye on the meter.