In general terms it's next to impossible to get 100 for reports, essays etc. It doesn't happen, really. There are always ways to make them better, and there is not a way to make them 'perfect'.
For written assesmsents, the rubric does not really tot up to 100.
Not sure how you could 'fight it'. 'Fighting' a first class mark would be very curious indeed, and you'd be challenging academic judgement, which is not allowed. You'd he challenging it on a first-class mark, too, which would be laughed at.