Why has my 'in debit' amount gone up after meter reading?

[PandaBearBear]

Sorry if this is a stupid question but Google isn't much help and I don't understand this.

After the energy price rise I was quite a lot of money in debit that I couldn't afford to pay, but my direct debit payments were raised to £285 a month to help pay it off.

For a while my meter readings have been estimated, and my 'in debit' amount went from over £1000 to £188 as of this morning.

Then, I was asked to provide meter readings online - which I did. My meter readings were lower than what they have been estimated from a month ago, but now I am over £500 in debit??
How can this be?

OK I'm in credit not debit but what happens is every month my direct debit amount is applied to my account then roughly every 3 months my bill is issued which reduces my credit balance. This sounds like the same has occurred here

It's because your bill has been calculated and taken off your account. It was estimated before and now it is accurate.
you were over £1,000 in debt before (when it was estimated) and you are now £500 in debt (accurate reading).

As pp said, your account balance is only correct right after a bill is issued.