Rohini Garage was very good on Ambassador. I heard that they too closed before few months.
I will try to get mechanic number who is very good for Ambassador and old cars.
I am from Coimbatore and i too having Ambassador Grand 2010. i know a mechanic who is ok, where are you in Coimbatore. i can refer you the person. i too changed some 3 to 4 mechanics and not fully satisfied with the work but somewhat it is ok.