u/Koraxys

Hey! I got a sent a fake/resealed pokemon simplified chinese booster box.
When i showed proof to the seller they told me its real and from a trusted supplier but i could send it back. I dont trust them to send it back because I think they are scamming, so i messaged support with proof of the box being fake/resealed on the 29th of April.
I still do not have a response and the shippment will automatically be confirmed on the 19th of May. What should i do? Should I mark as not arrived?
Thanks!