Impossible to know what's happening between you and the builder without having a lot more information. Are we talking about a big job, was p/p needed, are there conditions attached, what sort of money involved, was electrical work carried out and signed off by a registered electrician, was an engineer used to draw up plans, to monitor the work, inspect different stages of the build, who purchased supplies, what issues are you talking about, are there grants involved, etc, etc, etc.?