I have an electric Whirlpool cooktop (GJC3034RB02). It is 9 years old. The top right burner has a "simmer" on it as well as a regular burner unit. It does not operate except on HIGH. I have been quoted $460 to repair and replace it. What does just replacing the stovetop cost? Do you think this is a fair price? The repairman said it will 2-3 hours to replace the control knob.