Monthly bill jumped from £100+/- to £650

Just got this months email and it says

Hi Colin,

You’ve used £641.98 of energy since 24th August. Your account is now £34.72 in debit. We’ve attached your statement with more details.

£641 in a single month…
i know i moan at the wife to turn off the lights…
but this is getting silly.

Currently waiting for bulb to call back to discuss.

We've attached your statement with more details.

Currently waiting for bulb to call back to discuss.

Whilst you are waiting fro Bulb to call back, doesn’t your statement shed any light as to the amount of energy you have used and hence the cost?

Further to Allanr`s post does your bill state estimate or actual readings.