Techradar reports that Microsoft has loosened up its procedures for Office 365 subscribers to upgrade subscription plans using a wizard in the admin portal

It announced the change on an Office 365 blogpost, which indicates that it's possible, among a range of other changes, to switch from Small Business P1 to Small Business P2 but not to downgrade. Once the new plan is purchased, users are automatically reassigned and the company receives a credit for the unused portion of the previous subscription.Previously, customers had to manually reassign licences and call Office 365 support to cancel the old subscription.

  Microsoft relaxes Office 365 upgrade procedure