Do Octopus still head the top 10 of the energy suppliers? They rock.Lots of energy companies will let you pay whole amount monthly by DD.
Personally I am with Octopus, have smart meters and pay by DD. The app or online lets you change the DD easily. Had a smart meter changed within 6 weeks when the first one went belly up and pay 7.5p per Kwh for 4 hours a night to charge my car. 2 sessions gives me 160 mile for under £4.