How does Telecom send a message to change the traffic package?

You can't change the information directly by sending, you can only close the previous traffic packet and open a new traffic packet.

This depends on what the specific instructions are. Usually when you open it, there will be a relevant unsubscribe code. Send the code to unsubscribe, and then send the required traffic packet code to open.

If the mobile phone is replaced, you can only go to the business hall or call the operator's customer service, and you can't send a text message to change it.