You need to be specific on why you can't watch iflix. Is it the app not responding? Cannot log in? Best to get in touch with Celcom for them to troubleshoot for you. Here's how;
"As this is an account specific issue, please contact our direct support agent as we will need to have your personal account related information. You may click on this link https://www.messenger.com/t/celcom for assistance. Alternatively you may also call 1111 and speak to one of our Customer Service Consultants."
All the best!