Timmeh

I have recently purchased a 2013 Mercedes Benz E coupe. I have a bit of a problem with my parking sensors. They work perfectly fine but, I had two accidents due to the senors only beeping when you are about to hit something. The moment I heard the beep I hit full brakes in both situations and it was too late. I remember in my old C 300 sedan the senors use to beep so much earlier and I never had ANY problems. In this car it only beeps when I reach the 6th or 7th dash. How can I go about fixing this? I want it to beep much earlier because, this is seriously disappointing.

Thanks any suggestions are much appreciated