E320 Model 1995 Wiper problem?

[Qamar]

I have the subject car. For the last few days whenever i press the signal stick for going to right or left the wipers start working. Very strange. However if i carefully press the stick right from the bottom and not touching the tip of it then the wipers dont come out. It appears that there is some defect in the tip of the stick.

Any suggestions what i should do, as it is really very irratating. In mine area we have lot of sand and very fine dust is always there on the wind screen. So the moment the wipers witout water starts up they really can scratch the whole of the screen.