Changing billing cycle
It is possible to modify billing cycle without having to contact support. Please note, however, that if you have already received the renewal invoice, then the system will not allow making any changes until the invoice is paid. New invoices are generated on the Renewal date, which can be verified by following this link: GO

How to change billing cycle
Billing cycle can be changed on the following page:

Locate service you’d like to modify and click [modify] link in the Renewal Date column. Changes will be saved immediately.

Keep in mind that the changes only apply to future billing. It is not possible to make retroactive changes to already issued and/or paid invoices.