If you book with a TA, are you aware that OBC from them will not usually appear in your account until you board or the following day?
Seems a call to your TA is in order to determine the amount of OBC you have from Celebrity- which you can spend now- and the amount that will post after you board from your TA.
Also remember canceling an activity or shore excursion happens immediately, but your account will usually not get the credit for about 48 hours and the credits are processed by a different department.