Unable to update or download apps
I recently purchased a iTunes gift card to use on purchases and things. I entered the card and it's now on my account. My problem is that when I try to update my apps it tells me to verify my payment information. Why do I have to verify payment information on a free app, especially if it's just an update? Also, I can't even verify my payment info because the card that is on file I no longer use. So I was planning to change it to the iTunes card but it does not give me the option to remove that card. Can anyone help?
iPhone 6s Plus, iOS 9.2.1