Learnt this from a bitter experience using the service of contractors based on name cards. My water tank leaked flooding my bedroom and attached bathroom. I called a contractor from a name card - Wa Hup Construction renovation. Charged exhorbitant fees. Cheated by saying they changed the valves when they didn't. They refused to repair the ceiling they broke. Worse, they refused to give a receipt for the payment. Two days later, the leak started again. Tried to call them but the person on the other end kept given excuse that no technicians are available. Even not answering my calls to demand for receipt, repair of damaged ceiling and warranty document. Paid almost RM4K. Called them for out of desperation. They said they are based in Puchong near Tesco but refused to give address. Lesson learnt - never ever use the service of name card contractors. Get someone familiar and reliable.