Poshmark review: Scam setting up account 1

Poshmark said they were going to take 800.00 from my credit card account to authenticate the account. I was told they would hold it for 3 seconds then put it right back. Instead, they asked me to put in another 800. They kept saying not to worry that it would all be put back in. I was not able to put in another 800.00 so they still have not put my money back on my card. I don't know how people get the account set up if they keep wanting to take all they can from you. It should not require that kind of money to set up an account.