Sitelio Customer Service Issues

Hello, on the INTIMISSIMI website, I am trying to make a payment with a POSTEPAY prepaid card (Visa) and with a POSTEPAY EVOLUTION card (Mastercard, card including IBAN), but after several attempts, it keeps saying the card information may be incorrect or there is not enough credit. However, everything is in order with the cards, the data entered is correct, and there is enough credit. I would like to know what the issue is and why I cannot place the order. I am also curious if it is possible to pay cash on delivery due to this recurring difficulty and especially to confirm if the website is still active, which may explain these issues. I am looking forward to your kind response. Best regards. Alessandra