You may proceed to registered new number with Postpaid plan via our Online Store, kindlt visit this link for more latest plan from Celcom https://www.store.celcom.com.my/store/Plan.jsp
Just click View Details > Add to Cart > Click New Mobile Number > Sign Up to our Online Store to proceed further.
I hoped this will help you Tieyha <3
Sorry for the experience you had
Plz screenshoot of the display error for us to investigate further on this matter and kindly submit the required information via Contact Us Form https://www.store.celcom.com.my/store/contact-us.jsp