They have this tendency to deduct your remaining credits at the end of the month - and came up with the most ridiculous reasons! Example - deduct all of my credits due to "expired data limit" or "usage over data limit" while I'm on UNLIMITED DATA PLAN and I'M ON AUTOMATIC DATA RENEWAL!.
Ofcourse, reporting this to mcmc will yield no result, despite all the evidence being shove to the them "screenshot of the message from the celcom, receipt of the plan etc".
Celcom is a scammer, and always will be in the future.