Why won't my iPhone 4 update to iOS 7.0.3?

I have tried updating my iPhone 4 at least a dozen times to iOS 7.0.3.
I have it connected to Wi-Fi and plugged in.
I go through the same process by going to settings > general > software update > download and install.
It takes it at least ten minutes to actually prepare the update, then when it does it lets me know that it's going to install the update. The phone shuts off, I see the status bar, and it moves about 1/3 of the way only to stop updating and the phone turns back on.

Is anyone else having this issue? Please give any insight that you can.

Thanks!

Added (1). I have 2.6 GB available currently.

I had no prob updating. Could you not have enuf space for the new OS. Is the phone's memory almost full?

Do some searching but it looks like you need over 3 gb open space or more.

First you have to update your itunes to the latest version and then connect your phone to itunes and through there your software will be updated properly. Don't update directly as that will wreck your phone and you will need to do a factory restore.

My sons had the same issue. I tried over and over and it looks like it had updated but when I looked it hadn't. I found out it was because he didn't update to iOS 7.0.2 first. I finally got it to update by plugging it into itunes and doing it that way. Success.iOS 7.0.3 is now loaded.