2006 Hyundai Sonata no turnsignals

Since I got the car have had problems with the turn signals not working. I have taken it to the Hyundai dealership (s) many many times but when I get there they are working. A couple of times they were not working and was told they saw the problem and fixed them but I continue to have the problem. Hyundai refused to do anything unless they saw that they were not working. I have left the car there for a week telling them not to start the car for a few days so they would not work, but they would start the car every day, and the turn signals always worked. It seems when I am not driving the car every day for at least an hour at a time that is when the problem starts. I now take the train to work so not driving as much I rarely have turn signals when I do drive. The car is no longer under warranty, which doesn’t matter since Hyundai never did anything. I have been told by the mechanic at my local garage that they would look at it but may never find the problem. Does anyone have any suggestions on what to look for having had this problem?