Direct Debit and meter reading

I’ve 2 queries:

  1. I have 2 gas meters on my account, tried to provide a gas meter reading but can only provide it for 1 of the 2?
  2. After 3 months it looks like my direct debit is insufficient to match my energy usage. How do I increase the direct debit and pay the current owed amount on the account?

Point 2…Go to your account page, Then
Change my payment details