Poppyred Some suppliers will not let you do that.
I currently pay by quarterly DD. My supplier has just written to me to tell me in peremptory tones that it is not doing quarterly DDs anymore and is transferring me to a monthly payment, which it has set at £650!. At the same time it tells me that my bills this winter will be equivalent to an annual bill of £2,700 (we have a big and very old house), which by my calculation is about £225 a month.
This is the supplier who took £900 out of my account in June for the second quarters bill, and a few weeks later paid me back over £500 because it had made a mistake!
I am trying to transfer to another supplier but, under current conditions this is very difficult.