If your phone was susceptible to shutting down abruptly, there wouldn't be a lot you could do. At the time, unfortunately, no one quite knew why these phones were shutting down abruptly. You might suspect it's the battery. You could go out and buy an external battery pack, a battery case for your phone, so that it would have more longevity. You could take it into an Apple store and have the battery replaced at your own personal cost. Those would be the options available to you.
A video is available from Parliament.