With our main program, we include up to two additional classes in another program to enrollees. We provide a code to account holders to allow them to complete the enrollment, that allow up to a specific dollar amount off the enrollment into classes. The problem is that account holders have figured out that they can use this code multiple times to enroll in as many classes as they want, as long as they are broken into separate "enrollments". We need to the ability to allow a code to only be used once by each account holder.