Probably no need for an extension. When I called, I literally had the K-1 within 10 minutes after the call ended. You probably can't call today (I think it was only working on weekdays), but if you call Monday, you shouls have the K-1 in plenty of time to file.
This happened to me last week. On CPNO's web site, they ask you to either email them or call the 1-866-536-1968 the other poster listed. The e-mail was a failure; no one ever contacted me. I didn't have much hope for the 1-866 number, but it worked - I had my K-1 within 10 minutes.
Call the number, but make sure you have the following information first: name and tax id number (Social Security number) and history of your buys and sells. That is, they need to know how many shares you purchased and at what price, and how many you sold and at what price. They then create a K-1 for you and e-mail it to you within minutes.
That should solve your problem.
If you bought your CPNO units in 2009, they may blame your broker for not giving CPNO the proper information about you. The reason for the problem isn't important, tho. The point is that they can fix it really quickly.
Call them at Member Support at (866) 536- 1968 if you haven't already. The record should be listed under your SSN. If you've been getting distributions, your shares are there but perhaps listed under your broker's ID if held in street name. If that is the case, check with your brokerage firm as well.