You can LEGALLY refuse to complete without the LFO being issued and if it eventually reached Court the developer would loose the case and there is legal precedent for this
The problem is that it may take 2 years to get to Court and chances are by this time the Certificate will be available
The issue with lawyers is that if they have been recomended by the agent or builder they may not be as independant as they should be
There are all sorts of issues if you dn not have one, not just the connection of services, water electric etc but also, if you plan to live in Spain, issues with getting medical cover, and signing onthe Padron
I have a guide which explains more about this and includes a process, outside of going to Court and using the department at the local town halls who will help you with the builders and they are key to granting the license
If you would like a copy of the guide please mail me at cayetano@inspectahomespain.com