You can appeal. If it is mentioned in the letter, follow the process mentioned there. However, you can also submit a new application at JPN.
Our Office
D-3-33, Block D, 8 Avenue Business Centre, Jalan Sungai Jernih 8/1, Seksyen 8 Petaling Jaya, 46050 Petaling Jaya, Selangor, Malaysia
(only on appointment basis)