You should be able to get this back by chating with Customer Support here . They are the best way to handle subscription issues; have all of your information you can and give them the details. Chat is the fastest way to have this handled.
You may require this same Product Key for activating the Norton 360 3.0. You can download a new copy of Norton 360 3.0 from any of the following links according to the edition you have(click on the link to to start the download):
Then install Norton 360 using newly downloaded copy and activate it. After installing the Norton 360 3.0, run LiveUpdate repeatedly untill you see the message "No more updates". Let us know the results. You can get refund for the recent renewal(starting from December 2009) which you have made by contacting the Customer Service and continue using the previous existing renewal service.
You can reclaim the lost subscription if you have the old product key with you. You can re-activate with the old product key to get the subscription days back. Your expiration date will be set to March 2010 again as you have mentioned.
But please note that you will lose your current subscription days if you re-activate with the old key. For instance if your current subscription is upto Dec 2011, it will be replaced to March 2010 if you re-activate with the old key. But you can contact the customer service for refund as Yogesh mentioned above.
Just FYI: Please register to Norton Account so that your N360 key will be stored there and you can retrieve it for re-activation whenever your Windows is reloaded. By re-activating with the product key stored in "Norton Account" you will get back the subscription days instead of renewing the product again.