EXTENSION OF SCHENGEN VISA

hello,
I am Muralidharan, Mechanical Engineer from India.
Presently i am staying in germany in Schengen Visa. My
client requires to extend my stay due to Business
Requirements. I landed in Germany on 6th Oct 2007. I
will be completing 3 months on 5th of Jan 2008.
My Visa validity is 1 year.
Kindly let me know is it possible to extend my
schengen visa for another 3 months. Please reply as
soon as possible.