ur mechanic is fooled....
this is not the timing belt issue, if the timing belt is worned out, u can not even start the car.
but get it checked whether teh condition is gud or not.
may b the valves are leak, because in the cultus model u r having, this is a great problem that the compression is weak due to the leakage of valves thats y the pick id totally down and the car is driving very heavy........