2002 Blazer rear window wiper problem

I have a problem on my 2002 Chevy Blazer. I use my remote keyless entry to open up my doors. At least once a month or more when I open my doors, my rear window wiper begins to move on its own. Sometimes I do not know it is doing this, until I get into my truck and hear the rattling of the wiper on the back glass. I can get it to return to its normal position by turning on the truck and then flipping the switch to turn on and then off the wiper. This problem has gotten so bad that I have had to manually move the wiper in order to get into my back glass. It does not do this everyday but is quite a pain when it does do it. I took it to my local Chevy dealership about this problem. The first time they could not duplicate the problem. The second they changed the wiper arm and blade (which I asked them not to because I had just replaced it). I took it back to the same dealership for a third time last week to be told that there was nothing they could do about it unless I bring it to them while it is malfunctioning. Is there someone else who has experienced this problem, or does my truck just not like me?? Please help me!!

~Heather~