“Your payment method was declined. Update it or add a new payment method and try again.“

Contact your bank to see if they can see why it was declined.

If your bank can't see anything wrong:

Contact Apple for support and service - Apple Support

Good luck!

See the Apple Support article(s) below. Link to contact Apple Support in the article. 

Apple ID payment information - If your payment method is declined, or you have a billing issue with a previous purchase in the iTunes Store.    

Possible fixes.   Fix ‘Your Payment Method Was Declined’ Error In App Store

                          Payment method declined in iTunes or the App Store