I can't update payment details, the problem with my icloud

Dear Sir,

I can't update payment details at my iPhone X. There was a problem with my Cloud storage payment. I need to update my payment details to keep my 50 GB of iCloud storage but it is doesn't work. My credit card Visa failed. My payment method was declined. I was trying to update several times but it does not work. Would you like to help me.

Thank you.