Hello, first of all, thank you for your support to China Telecom. According to your description, your certificate has expired, so you need to go to the bank to apply again (no charge, no need to replace K-treasure, bring your ID card and bank card), then go back and download the certificate again, delete the original expired certificate (that is, settings-content-certificate), and you can see the validity period of the old and new certificates. Then it can be used normally. If you can't solve it, you can also log in to the telecom online business hall (/) for consultation. China Telecom launched a 4.5-inch big-screen mobile phone special event, and four big-screen mobile phones are available for you to choose from. The price is only 859 yuan, with ultra-high configuration and ultra-low price. You deserve it. The theme of related activities is as follows: For details, please visit Tianyi Store:/iphone/ext/4.5big/index.html.

Wish you a happy life!