As a matter of urgency I need to know if a company called Interstock Transfer, aledgedly based in Manhattan, exists and is arespectable company. They are putting me under some pressure.
Most likely a scam, can you elaborate on your dealings with them? Also you might like to read the boiler room scam thread here, you may find some very similar stories.
They were mentioned here in connection with a boiler room scam, it seems they may have been involved in the advance fee part of the scam ie offering to buy worthless shares from you for an advance fee (which they then steal and disappear)