It sounds like you are dealing directly with the title company and handling everyting on your own. If this is the case I would stop calling and actually go to the title company. Make an appointment and speak directly with the Escrow officer handling the file and find out exactly what documents are missing and if this is really the hold up for the closing. Get to the bottom of the issue. Call the bank together with the escrow officer and find out exactly who has the file and what is being done.
Also, make sure that your timeframe or closing date has not passed and that you actually still have a valid contract and that the bank has no reason for getting out of the deal.
You may have to get legal assistance or advise so you can get things moving. What ever you do, take action and don't wait for them to call you.
I am not sure why your Realtor is not on top of this, I can only assume you are not using one? Call Title, see what this "one missing paper is" and then get it signed and back to them and the listing agent. Good luck but I think it is worth the time to call the bank , every day until you finally get someone to speak to. It is in their best interest to close at this point and if you still want it, you wait BUT that should speed up what is left in the process.
Sorry this is not a faster or better transaction for you.
Best of luck.