Hi , Recently I had selected a ID contractor. Their payment terms is 20%(signing of agress & tiles confirmtion), 30%(upon commencing work),45%(upon measure carpentry works), 5%(completion of works). After signing agreement, he collected S$2000, from me, after I slected the tiles , he collected another S$3000 form me. Yesterday he say that he will start to hack the tile and want to collect the balance 50% of the total amount form me. My wife insist not to pay him the 50% as becuase he has not show us the 3D drawing and the detail concept dawing of our whole house. But he say that the drawing is not related to the hacking work, and say that he will hack first, collected the money first and then show me the drawing later by tonight or tomorrow, and he say that this is normal practice for ID. So like to consult anyone and let me know is it reasonable for his request? Thanks you so much.