
Dear @Senzo Ngcobo
Hope you to have a good day.
The following are the common steps to buy the Office 365 Extra File storage Add-On, you could check whether there is something wrong:
1.In the admin center, go to the Billing > Purchase services page.
2.At the bottom of the Purchase services page, in the Add-ons section, find Office 365 Extra File Storage, and select Details.
3.On the product details page, select Next.
4.If needed, choose the base subscription, then enter the number of gigabytes of storage you want to add.
5.Select Check out now.
6.On the How does this look? page, verify the number of gigabytes of storage you selected, review the pricing information, and then select Next.
7.On the Complete order page, verify the total. If you need to make any changes, select Edit order. If the order requires a credit check, select the check box. When you're finished, select Place order > Go to Admin Home.
You could also check whether your plan is eligible for Office 365 Extra File Storage: such as Office 365 Enterprise E1, Office 365 Enterprise E2, Office 365 Enterprise E3 and so on.
For more information about how to add more SharePoint storage to your subscription, you could refer to:
https://learn.microsoft.com/en-us/microsoft-365/commerce/add-storage-space?view=o365-worldwide
Your time and patience is much appreciated.
Yours faithfully,
Yi Lu
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