Hyundai Motor India — Radiator and head knocking

Address:

389230

My car no.GJ 17 N 4834 serviced by february 2 2016 in godhara ( gujarat ) but after service every two days coolent level is going less and water added by me.complaint of this metter by me to godhara by phone.but till to day this problem is running and due to this problem in head knocking is start and many problems creat .so pl.do needful