"They can’t even give a list of all my data under the GDPR so I can see myself, which seems illegal."

You're in Greece? Under the GDPR they're legally required to give you all the data they have on you; this is non-negotiable. I hope you included that in your complaint.

As for the rest, I guess they're just garbage and I'm glad to know I don't ever want to be using their services. Maybe someone from Revolut will chime in here and try to explain the situation.