Maruti Suzuki India — Complaining about reverse sensor regarding

This is LATHA.P. My car num is TN55AP2955.I had met with an accident at 1st JULY 2016.we got back after serviced from PLA MOTORS, Theera nagar, TRICHY branch at 15 of JULY 2016.After getting back from service they fail to attach REVERSE SENSOR.I requested them almost more than 20 times., they are not responding properly.so i had a complaint over them.Plz do the needful as soon as possible.