If I were you I would immediately cancel the direct debits, then phone them and inform them you cannot possibly afford to pay what they are asking. Ask if you can have payment cards, they should allow this and agree with you how often and how much you can pay, tell them that you will try and pay extra when and if you can to reduce the debt, dont let them bully you, it's not as if your saying that you wont pay back the money, as long as you are offering to pay a little more, rather than what they are demanding I'm sure they will accept this. You have to be assertive but not rude, just stress how difficult and impossible it is for you to make the payments they have suggested.
Who are your gas suppliers by the way?
Hi Tracey
I am with them too, so I know they do supply cards as I have them myself as I would not pay by direct debit, but wanted to pay monthly or you can pay 2 weekly rather than quarterly. I then pay the amount agreed or sometimes extra.
Dont let them fob you off with any other way of paying, they will want you to continue with direct debits but just be firm and say you cannot afford to have any more rising direct debits from your account.