Best answer by woz
It's irrelevant what the comparison website said, you can put any figure you like in the consumption box but it doesn't mean that's what you use. and with PP you pay for the energy you use.
Do you have any bills from your previous supplier to show what your annual estimated consumption is?
The first thing you need to check is whether the readings you have submitted are appearing on the statement, it could be your statement is still running on estimates which it nay do at the beginning.
If you have the opening reading and date and a latest reading and date you can work out what you've used.
Are you dual fuel user or electric only?
How much is your direct debit?
How much were you paying your previous supplier?
I used a comparing site which said my usage and cost would be around £50 to £70 pcm. My bills are now £150 to £200 pcm which is way more than I used to pay with last company.