Considering the information provided in your question, I would like to provide you with some guidelines. My understanding is that there is a penalty clause of 30 Euros per day, which is a reasonable amount. In this situation it is important to take into account that the delivery of your apartment has been delayed for one year, and such a long delay has not been justified by the vendor, either by reference to terms in the contract or other legal justification. Prior taking any formal action against the developer it is necessary to obtain evidence of your attempts to claim compensation for the delay prior to your signing the title deeds on completion. This can be done by arranging for formal letter setting out your claim to be sent to the developer by a Public Notary.

If the promotor rejects your formal letter for compensation my recommendation is that you sign the title deeds anyway. Otherwise if you do not and start legal proceedings through the Spanish Courts the delivery to you of your apartment will probably be delayed for a year or more. Once the title deeds are transferred into your name, you are still entitled to claim compensation for the late completion through the Spanish Courts.