Payment failure

The automatic monthly payment via mastercard did not go through yesterday/today. I called the bank and nothing is wrong with my account. I tried (multiple times) to add a new method of paying (first via paypal, than also via a different mastercard) but everytime i get the message 'A transaction can fail for different reasons, check again if you've entered your payment details correctly. If the problem sustains, you may need to enter a different payment method or contact your bank'

(original, in dutch: Een transactie kan om verschillende redenen mislukken. Controleer nogmaals of je je betaalgegevens correct hebt ingevoerd. Als dit probleem zich blijft voordoen, moet je mogelijk een andere betaalmethode gebruiken of contact opnemen met de bank.) 

I've tried the chat, but it's unavailable. I tried calling the Belgian number, but it doesn't go through. 

Any other options? Thank you for the help!