Poor correspondence/tracking student information/supp**** materials

I have found that oxbridge tutors/assessors do not track student information adequately numerous times on marked assignments in engineering i have been referred to a page in the study guide which is either blank, non related even missing from the received materials which is quite annoying, this also lead me to believe that my previously marked assignment on their introductory course was not marked on the material i had received and so i requested that they sent me the updated version of the assignment and surely it was so, the difference between the two assignments make it clear that my submitted assignment was marked in correspondence with the updated version where i lost 50% of my marks. I have asked the tutor questions and then they answer some random response but do not answer my question thus leading me to think why bother asking if you can not obtain a straight answer.