If a buyer has left a negative review and after sometime he got his job perfectly done from the seller.
No once reviews left they can not be changed or manipulated.
If order automatically marked completed after 3 days of delivery.
Then buyer can leave a review upto how many days?
Buyer can leave a review up to 10 days after the order is marked as complete. It’s clearly stated in the ToS.
Since this isn’t the first time you ask about something that is explained in the ToS, perhaps it’s high time you read the terms of service? Carefully, from beginning to end, several times if needed?