There is in Spain a legal procedure whereby you can voluntarily transfer the asset back to the bank through a notary. The fees involved are small in comparison to the asset value of the problem. You surrender ownership (and take the hit) on condition the bank does not chase you and it avoids bankruptcy which is never desirable. It involves simple signing of papers you and the bank.
There are conditions of course but the size of your debt to asset value seems small. (30K)
Your lawyer can advise you better.