Can't restore my iPhone5 because it keeps crashing.

A couple months ago I bought an iPhone 5, however about a month ago the phone started going black and not coming out of standby for a couple minutes.

More recently the phone has been crashing at random times continuously then randomly stopping. The screen will transition from the screen i was on with partial lines, into a faded colour like green, and turn off. Then on rebooting, will do this with the Apple logo, and repeat until I merely turn it off (pressing standby and homescreen) and leave it aside for a long time, or other times after a few continuous crashes the phone will start working again.

Earlier, my phone started crashing then came up with the *plug into itunes sign*, which I did, upon the iPhone restore it came up with an "unkown error occured (9)". When looking at the screen trying to restore again I saw my iphone crash during the restore, cutting it off I guess because I know the cable and the USB port are fine.

I have spent the majority of today sifting through the community forums hoping that someone else had this problem (and they'd solved it, i'm not evil), I would greatly appreciate any kind of advice. Whether it's something I can do or just take it back to the store.