dvd problems

[george54]

to cut a long laborious story short where do I find the unit where the dvd player, the sat nav,tv radio all plug into ? in a RR vogue se fitted with a rear entertainment system. Im told its a silver box about 12 inches long by about 6 inches possible part no starting with FIL basically it this is where the fault in my system is (DVD player shows incorrect video signal) a trip to my local dealers almost led me to scrapping the DVD unit as they swore blind it was faulty and at £999 for a new one I had a second opinion from the manufacturers Alphine and guess what it works perfectly and they state the problem will be in the control box that all the units lead into but I have been over the car and all the wires disappear from the rear compartment into the bodywork of the car can any one point me in the right direction or even supply the name of the unit?