I clearly remember that the ICBC card didn't have SMS notification. Why is there a reminder of balance change? Do I need to go in person to change the reserved mobile phone number?

You have two questions. The first is the reminder message of balance change. It is possible that you have opened the e-Unicom service of ICBC, and the SMS reminder of this service is free. If it is not e-Unicom business, I suggest that I bring my ID card and bank card to the bank business hall to cancel the SMS reminder service. In addition, if you want to change the reserved mobile phone number of ICBC, you must bring your ID card and bank card to the ICBC business hall to change the mobile phone number, otherwise you can't change it at will.