I have a customer using a not for profit version of G-Suite.  Its working fine except they have a user thats sitting damned close to their 15GB allocation.  They are more than happy to pay for an upgrade to 100GB or whatever but I dont seem to be able to find any information on how to add that on.  Anyone got any suggestions? 

Before anyone asks I have checked out how to add it into the billing and theres no options on it like there normally would be.  Heres what Ive been referencing.  Im thinking I may have to contact Google about it. 

Assign, unassign, and reassign licenses