Why is the contract automatically renewed? How to change it? Or cancel.

According to the information you provided, the change of the package during the contract period will be limited to a certain extent, and different contract plans have different rules. I suggest you contact your Unicom customer service. Usually, when the old contract expires, it will be renewed by SMS or telephone, and it will not be renewed without reason. You can pay attention to whether you have received the relevant notice. Specifically, you can also contact your Unicom customer service, subject to local policies.