Why do you need this module?
Keeps its hosting customers happy and makes possible dropouts in upgrades. You are also someone's client and you know how you like being treated, use that to your advantage.
Economy in support and less time spent answering questions and solving customer problems. Or do you prefer to keep writing those e-mails filled with excuses and answering calls?
The customer is grateful to know that his business is growing and it is time to invest more when you anticipate the negative actions of an account lockout. Would you rather have the customer walk away complaining or make you hire bigger plans and generate more $ for your company?
Tags for email templates that accurately report in % and MB the use of the account + tag that generates direct link to the upgrade page. All highly customizable. After all, who does not like to be well informed?