Hi colin777a
Thanks for letting us know.
This sounds right as your bill was produced before your cancellation, you'd be charged as normal for your services.
Don't worry, as this will likely mean you'll have overpaid for your services past the date of your disconnection, you will receive a credit refunding back the incorrect charges.
If you haven't already, you should receive a final bill from us (the bill you're referring to is not the final bill) as this is produced after your disconnection. Everything will be recalculated from there.
Hope that helps. Let us know if you do have any further questions.