There are a few scenarios where you may pay in addition to your existing package credits that have been applied to your appointment.
If you have a package of blowouts and book for an updo which costs more, additional credits will be subtracted from your package to cover the cost of the updo. This will leave your package with an uneven amount of credits. When you use the last of your credits you will have an additional charge to cover what the credits did not cover in that appointment.
If you have a blowout package and book a blowout plus a manicure, only the blowout package will apply and you will be charged for the manicure.