Not convinced that that, in and of itself, is a dark pattern.
Now using that to essentially get customers to overpay over the year, feels like it might be. Guess it depends on how much you save with them in the first loads using DD.
Bills not paid in time is definitely an issue. Having access to charge you when needed reduces the proportion of upaid bills, so you get more money in time.
> Savings: Gas and electricity unit rates are lower if you pay by Direct Debit, saving you £100 in comparison to paying when you get your bill.
This is a fairly common discount to receive from energy suppliers, as direct debit payments have reduced administrative overhead compared to payment on receipt.
Fair enough, but given how crap utilities are at securing user accounts, I do not want to have an account with them. Just send me the invoice and I'll pay it. End of story.
Now using that to essentially get customers to overpay over the year, feels like it might be. Guess it depends on how much you save with them in the first loads using DD.