Just now Unicom sent me a text message asking me to pay, but I still have 640 yuan. What happened?

Hello, this may just be a reminder. If your account balance is not the balance of the returned amount, it should not affect the normal use. But if this 640 yuan is a reserved account, that is, the money to be refunded every month, it cannot be counted as the account balance. You can call 100 10 to check the balance again.