The requirements for the cedulla is that if  the  house was built years ago it must be registered as a house in the Land registry  before August 1984. The cadastral might say you have a house and you may be paying taxes but unless it was registered in the Land registry it is not worth the paper its written on. You can go to the Land registry and ask for these papers from before 1984 to see if your property was registered costs around 60-70€.It is not a problem to have Casa put on the escritura ,the notario is willing to take around 1000€ to do this but when selling need the cedulla or its an almacen,so as it is I dont think its worth paying a 1000€ .Things need sorting out urgently