After an order is completed on the Marketplace you are invited to review the seller/buyer you made your deal with.
Once a review is given it's not possible to change it afterwards yourself.
You can open a ticket and ask the administrators to change it, they will do if the request meets one of the following requirements:
1. The request is send by the person who gave the review. (p.e. he made a mistake and wants to correct this)
2. It's obviously a unfair rating, p.e. there's a one star given on the delivery speed while the bottle was shipped the same day the payment was made.
More info about the working of our feedback system you can find here: