Cannot change billing bank account

I tried changing my bank account from:

 Producten → Persoons- en betaalgegevens → Betalingsgegevens

After I change my account, on top of the page it says “Uw wijzigingen zijn verwerkt.” and the iban seems to change. But after I refresh the page the old IBAN is back. I cannot change my IBAN. The old one keeps staying. Is there another way to change my bank account?