You will need to contact Koodo to add an authorized user. You probably will need to call 611. Thatsvwhat others here have been told though Koodo says the only thing you cant use Facebook Messenger or DM via Twitter for is to cancel an account.
Is she on this account in any way? If she is you could make her a manager of the account by logging in to self serve. Click on 'my profile' then beside role management hit manage. You can make her a manager of the account in there.