i have problem with deposit now is over 5day
i was sent my stellar to poloniex wallet
you can post in announcement thread poloniex
or you can sending support ticket in youre poloniex account
back to OP, if you can buy bitcoin use fiat money in poloniex, only support USDT in there, you can deposit in tether.to use youre debit card
after you have USDT balance you can deposit in poloniex, and then buy bitcoin