Verification failure

I just noticed my apps weren’t updating automatically. Every time I go to update an app or get a new one, it asks for verification and I have to put my security code in for my debit card. Then it tells me my card is declined. So now I can’t update any of my apps or download new ones. I’m not sure if I need more money in my account because all of my apps are free except Netflix and that comes out by automatic draft.