Dash Wiring problems of the 2002 Hyundai Elantra

My clock in the dashboard blinks and loses time. I took the car to the dealership and was told that the wiring harnesses in the doors of the car had corroded and caused shortages occasionally in the dashboard. I was told this could affect the clock, the dashboard lights, and possibly the headlights. We have also had problems with our headlights staying on after they were turned off and the key was removed from the ignition. The cost of this job would be $900. I'm just very concerned that I will be driving at night and my headlights or dashboard lights will fail, causing a very dangerous situation.