Add-ons can be attached at any time, not only at the original order.
HOW
Services > My Services > click the service > Addons. Choose what you need and pay.
BILLING
An add-on usually adopts the parent service's billing cycle, with the first charge prorated to align the dates. It then appears as a line on the same invoice.
WHAT IS TYPICALLY AVAILABLE
Dedicated IP Additional disk space Paid SSL certificates Additional backup retention Priority support options
BEFORE ORDERING ONE
Ask whether it solves the actual problem. Extra disk space does not help if the real limit is inodes. A dedicated IP does not help SSL. Extra backup retention does not help if backups were never configured.
Open a ticket describing the problem rather than the solution, and we will tell you whether the add-on is the right answer.
CANCELLING ONE
Request cancellation from the same screen or through a ticket, choosing end of billing period.