Rental is charged in advance. Usage is charged for the previous month in arrears.
When you start a new plan or change plans half way through a month, the system will calculate a charge from the date the plan started until the end of that month.
This results in a part-period charge on your next bill along with a full month of rental in advance in the usual way.
If you are changing from one plan to another you will see a part-period credit for the time you did not use your current plan and a part period charge from the date you swapped plans until the end of that month.
If you have any queries about your bill you can contact our Customer Service Centre by emailing firstname.lastname@example.org