LTS

I bought a brand new 2015 Silverado on a Sunday and that next Friday, took it on a trip to California. At times, when going 75 MPH or above and a crosswind, the noise seems to be coming from the driver side door area. It is go bad, you can't hear the passenger talking. It doesn't happen all the time, seems to need a crosswind. There are blogs all over the internet about this issue, but when I took it to the dealer, they said they never heard of it and can't fix it, if they can't duplicate it (which won't happen on city freeways). I was hoping some one on this forum had a solutions. I wonder why the GM reps don't get involved??