I. Scope of Services

1. The after-sales service provided by this independent website only applies to tutorial document products purchased through the official channels of this website, including but not limited to electronic documents and online reading permissions. The website shall not assume any after-sales responsibility for products purchased through non-official channels.
2. The after-sales service covers ensuring the integrity of the tutorial document content, providing support for normal access, and giving version update reminders. It does not include usage problems caused by non-product-related reasons such as users' personal device malfunctions, network issues, or operational errors.

II. Return and Exchange Rules

1. Given the virtual nature of tutorial documents, once a user successfully obtains document access rights or completes the download, returns and exchanges are not supported, except in cases of serious content omissions (where the missing content accounts for more than 30%) or key information errors (affecting the understanding of core knowledge points).
2. If a user discovers the above-mentioned quality issues in the tutorial document, they need to provide clear problem screenshots, order numbers, and other supporting materials to the customer service within 7 natural days after purchase. After verification and confirmation by the customer service, the user can choose a full refund or exchange for another tutorial document of the same value.
3. Return and exchange applications due to users' personal reasons (such as mistaken purchases, duplicate purchases, dissatisfaction with the document content but without quality issues) will not be accepted by the website.

III. Content Update and Maintenance

1. The website will optimize the content and update the version of some tutorial documents according to industry trends, knowledge updates, etc. Users who have purchased updatable version tutorial documents will enjoy a free update service within 1 year from the date of purchase. The updated content will be notified to users via in-site messages or emails.
2. If there are significant changes in laws, regulations, technical standards, etc. related to the tutorial document, rendering the original content invalid, the website will launch an updated version within 30 working days. Users can obtain the updated document for free with their original order information. If the update cannot be completed within the specified time, a full refund service will be provided to users.
3. To protect users' rights to obtain updated content, users need to ensure that the contact information (mobile phone number, email) reserved on the website is true and valid. The website shall not assume relevant responsibilities if the user fails to receive update notifications due to invalid contact information.

IV. Technical Support Services

1. During the use of tutorial documents, if users encounter access failures (such as inability to open the document, abnormal page loading) or format compatibility issues (such as the document cannot be displayed normally on the specified device), they can contact us through in-site customer service, customer service email, or customer service phone. We will respond within 24 hours on working days (Monday to Friday, 9:00 - 18:00, excluding legal holidays) and provide technical solutions.
2. Technical support services do not include providing users with personalized learning guidance or document content interpretation (extended interpretation beyond the scope of the document itself). If users have such needs, they can consult the relevant value-added services of this website.

V. Privacy Protection

1. During the after-sales service process, we may collect users' order information, contact information, problem feedback content, etc. The collected information is only used to provide after-sales service to users and handle problem feedback. We will strictly abide by the "Privacy Policy" and will not disclose users' information to third parties (except as required by laws and regulations).
2. Users need to properly keep their account information. The website shall not be responsible for after-sales service disputes or losses caused by account theft, password leakage, etc.

VI. Terms of Effectiveness and Change

1. These after-sales service terms come into effect on the date when the user purchases the tutorial document product, and the validity period is the same as the service period of the product that the user enjoys.
2. The website has the right to modify these terms according to business adjustments, changes in laws and regulations, etc. The modified terms will be announced on the website's bulletin board and will come into effect 7 days after the announcement. If the user continues to use the website's after-sales service, it is deemed that the user approves the modified terms. If the user does not approve, they can stop using the relevant services, but the after-sales service for the purchased products will still be carried out in accordance with the terms before modification until the end of the service period.