I echo all the advice of all the other academics on this thread. Academic judgement & evaluation (ie assessment) is not grounds for an appeal, and your course leader really should not have said what s/he said to you.
Did you talk to the markers first? Did you engage with their narrative feedback on your work? There is more to assessment than the numerical mark.
If it's been either double marked or moderated, at least 2 people will have looked at it. They may well have adjusted the mark already. It may be that there was already a discussion about the grade, and the final mark you were given is a compromise between the two markers. This is normal. There will always be different judgements on essays, and this is NOT evidence of bias or incompetence.
And I might well want to check what books had been used in an essay, because of plagiarism. I once suspected plagiarism, went to the library, found the book on the shelf, with the suspect passage highlighted with asterisks.
There was direct plagiarism.
You need to be careful that your disappointment at one mark for one piece of work becomes something else. My advice is, move on.
It's rare for academics to have the mental or emotional energy to have a prejudice against students. Really. Generally, we just don't care in that personal way. We assess what is in front of us, and we want to see good work.