HP DVD Writer — delay in replacing

Dear Sir ,
I kushal thadani want to state that since 17th of nov , I hav given my laptop for replacing dvd writer which comes under warranty period.but till now it has not been replaced.
My friend provided the lappy for the same and his was done within a week ....
why this is happening .lalani computech is the service centre where i gave my laptop.. please do somthing if something can be done
thanking you..