I am surprised that a person like Sonuji has a hard time trying to get hold of Aamir Khan. Probably his secretary basically screens and blocks out almost everybody.
I thing you have to remember that Aamir Khan grew up with Uditji. They were so close from the begining. You can not say Aamir helped Udit or Udit helped Aamir for the stardom.
Now may be its Sonuji's time. But still general public get used Udit's voice in Aamir's face. Same what people used to see Rajesh Khanna and Kishoreda or Big B and Kishoreda or Shammi Kapoor with Mohd Rafi.
Film producers do not like to take that chance.
Sonuji came to Bombay in 1990. But after struggling for 7 years in 1997 he got exposure and the hit in "border". and every thing became history after that.
So my main point is that the MD and Movie producers in Bollywood never take a chance; Unless you are one them.