Are you given less petrol than what you're paying for?

Denise Xuereb writes:

'Over the past few months I haven't been getting the amount of fuel that I have paid for at petrol stations. To check whether I'm being given what I pay for, I have purchased a state-of-the-art five-litre measure and have found out that I'm always given a considerable amount of fuel less from every petrol station where I have filled my five-litre measure. The cost of fuel is already high. It is unfair that as consumers we are overcharged in this manner.'

I ask readers who are not being given the fair amount of petrol for which they are paying for to write to me naming the petrol station.