Since u learnt from an Israeli then I fear u. Israeli hackers are the most dangerous hackers worldwide. Even Chinese and Russians hackers respect them.
Most fuel attendants are crooks. If they sell to okada or keke before you, they will not zero the meter. They will smile and start irrelevant gist to distract you and then they start filling your tank. So if it was N500 or 1k they sold to the keke before you, that is how much you have been scammed. Always confirm the meter has been zeroed before they start filling your tank.
na wa. These yahoo boys don spoil Nigeria name so tey sophisticated internet crimes wey Chinese and Russian mafia dey run them go still say all na Nigerians dey run am.