Pertaining to the below email from you, there are 3 ways to upgrade storage:
1) Upgrade the whole domain to Google Apps Unlimited, USD120 per user
2) User buy individual storage for themselves
These storage need to purchase by user themselves using their personal credit card, is not done by reseller or admin. Also, the upgrading only can be used for that user only, cannot transfer and not under admin control.
3) Admin to purchase storage and assign to users
These storage belong to the admin and can assign to any users, can be reused. Pls note that this drive storage is per licence per user, cannot share storage with other users. You only can reuse when the particular user was deleted from console.
For upgrade Drive Storage request, pls submit the below online form.
Pls note that those are monthly price, we charge annual. We will pro-rated the price to align with Google Apps’s primary end date. The pro-rated price according to the date you request for add on.
Hope the above clarifies your query.