Is it permissible for a student to remain in their university major, which they enrolled in with the help of an employee, given that their baccalaureate average was not sufficient for admission?

There is no objection to you continuing your university studies, because what you did was neither cheating nor forgery. Your grades in the subject were good and deserved the estimation, and the impediment might affect the student's performance in the final exam. The student's past effort should not be annulled as long as it was excellent, and the school administration is the one that allowed you to do so based on your previous grades. You should improve in the future and utilize your knowledge and effort to serve your religion and people.