Holiday season is here, so petrol prices go up. What a surprise eh? Tesco near here is selling petrol for £1.40 pl. Tesco 3 miles away is selling it for £1.44 pl. During the parliamentary inquiry a couple of months ago, the price went down. What a coincidence eh? Having been dragged into the commons, the petrol free-for-all is allowed to continue.
Supermarkets used to sell their petrol cheaply to try to draw people to their stores. They have now decided not to price so keenly, presumably because they don't think it really works.
They are quite within their rights to do that. No amount of bluster can force them to.