Octopus, British Gas, EDF and OVO customers with boiler could save PS100 this summer / Octopus, OVO, Outfox, E.on customers given Martin Lewis 50-day warning / OVO, British Gas and Octopus Energy offering winter freebies worth hundreds / OVO giving customers a year of free heating worth over PS340 / Martin Lewis urges British Gas, OVO, EDF, EON, Octopus customers to take act now / Octopus Energy, OVO, British Gas and other customers face 24-hour warning over bills / Martin Lewis says British Gas, EDF, EON and OVO customers get PS135 boost this week / British Gas, OVO, Octopus Energy and E.ON customers urged to check if they're owed PS315 / Starling Bank poaches Ovo chief for next phase of growth