HELP! MY IPHONE WILL NOT ALLOW ME TO UPDATE MY FREE APPS WITHOUT BILLING INFO?

Ok so my App Store hasn't let me update any of my apps because it's saying I need to put in proper billing info, when I do it never goes through? All my apps were FREE so why can't I update them & why is it asking this? i've been having this problem since I've updated to the ios7

Additional Info

I have a iPhone 4s

I've bought apps before but deleted them

All my apps are mostly Facebook and Instagram