well most likely u r fucked up machan... because what they will tell u os that they are not repairing the orginal alarms or navi and they will try to fix u a one with what they sell....thats when they get the profit no... repairing the originals wont get them much of a profit.... sooo i cant think of a one who can do the both f them...
i dont get the problem clearly mchan... is it the navi that keps shouting or is it coming form the vehicle... if it is the navi then find someone who knows japanese... then he might be able to change the language......
but if it is coming from the vehicle... take it to the company....