Customer service is terrible. Once a transaction has been completed (which is done when the buyer submits a review), Mercari refuses to do anything to help a customer. They also have a crap review system/policy that allows sellers to leave retaliatory feedback for any reason (which happened to me after giving an apparently mentally ill seller 100% POSITIVE feedback... She was upset that I left feedback the day after getting an item... She thought I should have done it right away. Mercari defended her! Their response was that I should have been faster to leave feedback... Wtf their own policy is 8 DAYS and even then it's not mandatory.) Deleting this app, never using it again.