It seems to me that the gradation is due to the same randomness, which does not happen very often, but such events are hard to ignore. The only option for me is to review and perhaps ask the questions that caused this grading. You could also try to attach a kind of argumentative essay to the repeated grading, if need be there are examples at https://gradesfixer.com/essay-types/argumentative-essays/ in case you don't know how to spell it. But the main thing is not to throw up your hands and I think that the grade can definitely be raised, especially in your case.