Question about bill

[#1]

I transferred my broadband to a new supplier on the 7th August.  My telephone line was transferred on the 10th August.  Why therefore do I today receive an email informing me that Plusnet will be taking a full months charge for the period to the 9th September?

[#2]

Hi vidusi, basically the invoice was generated prior to the last of the services migrating away.
Once the payment has cleared, our billing team will certainly issue a refund for the overcharge when fully closing your account.