Apple iphone 4 16GB factory unlocked boxed with all the accessories +

Apple iphone 4 16GB factory unlocked boxed with all the accessories. Selling due to an upgrade, handset is two years old, slight scratches on the back but nothing obvious. The phone has a slight fault, the phone likes to turn off on its own every now and then. When this happens i just turn it back on and it fine. If you have it on all day it happens 2 - 3 times a day. I dont know what is causing it to do this or how much it will cost to fix. Open to offers and you can view and pay cash on collection