Sorry a bit offtopic from the question that u raised ,
"People in Mangaluru don't speak Malayalam"....Really ?
Actually as per my experience in Mangalore,its the opposite.SOME can speak.
In mangaluru central i have heard even RPF talking in malayalam.
Shunters...
more... talking in malayalam.
Most of the shopkeepers taking in malayalam.
Ticket booking office people talking in malayalam.
AutoRickshaw people talking in malayalam.
The one who cleans Retiering rooms talking in malayalam.
Sorry,this is what i experienced in my journey to MAQ last Year.
So Some can talk malayalam ,so your comment "People in Mangaluru don't speak Malayalam" is wrong according to my travel experience.