For users who wish to upgrade their accounts, this can be done from within the Client Control Panel. Additionally, in some cases, in order to ensure the resolution of advanced billing issues, you will be required to provide the agent who is assisting you with verification of account ownership, for security purposes. For both items, we have created guides to ensure that you are able to seamlessly complete both tasks when necessary. These guides can be accessed here:  

How to Upgrade 
How to Verify your Account