Typical of Sprint
If a customer's plan is eligible for the add on at no cost as this one is.....................just add it on Sprint.
Or make it known in LARGE PRINT that the customer has to call to have it added.
EDIT:
I just checked. Take a look at this >
http://anymobile.sprint.com/
It is supposed to be added on AUTOMATICALLY ON THE NEXT BILLING CYCLE.
YOU DON'T HAVE TO DO ANYTHING, as per Sprint's Ad.