For the past 2 months they have overcharged me, this resulting in me being £100 in credit. I've asked them to reduce the monthly direct debit, which they have from £84 to £40 based on my meter reading. I'm a very low user and £40 (gas and electric)is about right for the winter months.
What are my rights regarding the £100? Can I request they refund me (say £80 and leave £20 in credit) or ask them to put in nil amounts for the next 2 months direct debit payment? I've only been a customer for 2 months and paid by cheque with my previous supplier.