Many companies that actually use large amounts of fuel (supermarkets) or buy otherwise from oil companies could argue that they buy at fixed prices, often fixed months ago so possibly an argument for why they are stuck with higher prices

That doesn’t apply with the fuel producers who are also retailers (Esso, Shell etc) as they would then gain on one hand and lose on the other.

Basically we are all being ripped off. It is a disgrace that governments don’t act to break what is basically an illegal cartel of price fixing