You may be able to get them to reverse the original trade and/or credit your account back with the funds they removed to make the original trade happen, just guessing. It sounds like the issue is that they took your money for the shares and simply gave you an electronic marker (IOU) which looks like a legit trade of real shares in your account but there actually were not any real shares available in the market that day; they may have thought that they could over the days go back into the SFIO market and find shares to deliver to your account but with the DTC suspending services it caused a liquidity issue and so they may just not have any shares available to deliver to your account.
I would suggest calling them and get someone at the firm to credit your account back with the cash they took out to finance the trade, unless you want to wait and see if they ever deliver real shares to your account. I know its a bad situation but if your brokerage cares about your business, I should think they would either deliver real shares into your account at some point or else just reverse the trade for you.
GL
$SFIO!
News 
Market Data 
Discover 
AI
