Best answer by woz
CR means you're in credit, DR means you're in debit.
You may need to up your dd (direct debit) amount to bring yourself back into credit.
The dd is normally taken in advance (at the start) of the billing period, (unless you've changed the date of the dd), at which point you would expect to be in approximately one months credit. If you've gone into debit you aren't paying enough for the amount of energy you're using.