light switch 1996 sunfire

Firstly, I know nothing about automobile wiring, however if someone could help it would be appreciated. I have replaced the light switch in my 1996 sunfire 5 times.

The switch turns the night lights on and after a few months starts acting up and you have to jiggle the handle to put the switch on. The first time it happened a new switch was installed by my GM dealer and it lasted for two years. This fall it went again and I took my car  to a local shop and the switch was replaced. The switch was replaced two more times - my mechanic buys from the GM dealer who after the third time would not warranty the switch and asked me to bring the car to them.The GM dealer replaced the switch and then said it might be cracking each time because of the wire harnes which he replaced. Naturally, he would not warranty the switch, nor the harness and charged me $240. (Canadian). He also said he would not warranty the parts as he wasn't sure if he fixed the problem and the only way to be sure was to trace the wiring to see if someting was shorting out. He said to search for a possible short would be straight time and at $75.00 per hour (Canadian - about $45 U.S) I could run up quite a bill and they still might not find anything. It is my understanding that each time the switch cracks and then stops working. The switch itself is $100 and it is starting to add up and I feel like I am paying through the nose and no one seems to be sure what is causing the problem.

Any suggestions.

Thank you,

CAOCAO