Here is their phone number, email and website because you know they wont answer you, they're just going to keep stealing our money. 855-464-7482 website is mercari.com and email is contact@mercari.com
Im also contacting the BBB. Others may want to as well. Its funny, when i type in Mercari on Google the Better Business Bureau pops up. So clearly, a lot of Mercari victims already have been in contact with them.

Using Mercari is a waste of time IMO. Feel free to email or call them though as Megan suggests. File a chargeback with your credit card for item not as described. Contact BBB, maybe attorney general. STAY AWAY FROM MERCARI, they are bad news.