Not that it ought to have happened, but one should never use a debit card to purchase future services, whether that is from an air carrier or through a third-party vendor such as Expedia.
Yes, you will be made whole, but it will take a lot of time and work and you are out the EUR 4,000 until then. With a credit card, the "hold" would either never materialize as a charge or would have been temporarily credited through a chargeback pending investigation.