I have refused to purchase any of my fuel from BP, Shell, or Esso, since the pandemic started, once they put up their fuel prices, they are the first to raise them and last to let them drop.
Only way to deal with these giants is to mass boycott their fuel garages, it will let them know we are not going to stand for it.
Trouble is though we the British/English cannot stick together on anything, so it will never happen.