If you need to complain about Taobao merchants on 12315, you need to fill in the operator information.

Here are the detailed steps:

1. Open the 12315 official website, find the "I want to complain" button at the top of the page, and click it to enter the complaint page.

2. Select "Merchant" in the "Select specific complaint object" column, and then select "E-commerce website".

3. Fill in the store name and website of the merchant being complained in the "Merchant Information" column, and then click "Get Merchant Information".

4. In the "Basic Information" column, fill in the name, ID number and contact information of the merchant's operator.

5. In the "Complaint Matter" column, describe your complaint content and requirements in detail, and upload relevant evidence.

6. In the "Complaint Form" column, select your complaint method and accountability method.

7. After verifying that the information is correct, submit the complaint. You will receive a confirmation email to prove that your complaint has been successfully submitted. Please note that it is very important to fill in the operator information, which will help the relevant departments to accurately identify the true identity of the merchant being complained.