Intermittent emergency flasher (7x) when brake applied.

2010 Package 4 with uprades needs help!! We had foglights and the remote start added, and the car is great... except for one thing. On occasion when you depress the brake the emergency flashers blink 7 times, then stop for a few seconds, then blink 7 times again. Happens at start and also during driving. After some time of this, it stops?/? This is unnerving when you can't indicate to other drivers what your intention is, dangerous also. Has been to dealer numerous times, but of course can't duplicate error so dealer is dumbfounded. Any help or suggestions?? thanks