Shopify Payments - failure when customers go to pay by credit card

[azecom]

In my online store I use Shopify Payments and throughout this week I have had 2 customers tell me that they have NOT been able to pay with their credit card in my store.

I spoke to one of the customers on the phone and tried to help him live, but was unable to. The customer confirms the purchase with his bank, the bank asks him to return to the payment screen of my online store and instead of processing the order, he is asked again for the data to pay again... And so on in a loop.

All my customers are from Spain, they pay in €.

What is going on? Is Shopify Payments giving any problems lately?