You save nothing. There's a manager who needs to show more people switching to online accounts and they want to achieve it by brute force.

You save money when you pay energy bills via monthly direct debit, the direct debit unit rate is slightly cheaper.

https://www.britishgas.co.uk/help-and-support/bills-and-paym... says nothing of the sort.

That page is for their home services (e.g. insurance). For energy it's: https://www.britishgas.co.uk/help-and-support/bills-and-paym...

> 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.

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.