[AC Question]

Hi everyone,i have a big problem and i really hope someone knows how to help me

I have a normal galaxy s6,everything works fine,but when i try to buy something in app (or simply try to buy a game or a song) i get the following message: Your payment method has been refused.The message appear in every app i try to buy something,either with my google play credits or with a mastercard

Can someone explain me why i get this? I live in Italy,but under the method of payment section of the google play guide it's said that a mastercard works everywhere,so i really don't know why.Thanks to everyone that will answer me,it's really important