Mercari review: Unfair practices

On January 20th I purchased an "Authentic Coach Wallet, New with Tags" from Seller Gripsty for $35.00. I confirmed with her several times that the item was new/ I received the item on the 25th of January. Upon opening the package, I contacted Mercari and the Seller immediately as (1) the wallet was not an authentic coach (2) it was not new - it was actually damaged and marked up with rips and tears from every day use and (3) no tags from coach were included in the shipping. I was told to ship the item back to Seller by January 31st. On January 29th I requested an extension to ship the item back as my daughter was deathly ill in the hospital and I couldn't leave her side. That extension was granted. On February 1 I shipped item back to seller. Received notice from Mercari that date that it was too late, the funds were diatribes to the Seller as it was after the 31st deadline. I explained I was given an extension - they basically said oh well, you're out the $35.00. So this seller faces no consequences of fraud? She gets my money and the pathetic wallet back? And I get nothing? Not even help from customer service? I wonder how often this happens!