I am a new TA, this is my first semester. I am still working my way through things and learning. I have one group of students who are complaining about their project grades, but they showed up late for their presentations, did not turn in half of the assignment and didn't even look at the rubric that I handed out in class and posted online. They do not attend class regularly, they leave early/show up late and they generally just are disrespectful. They have never once asked me for help or emailed me on a regular basis to clarify things.
They continue to hound me via email asking me why they received the grades they did. I gave them a breakdown of what they were missing/what they did well and they are straight up trying to argue with me. I told them I would meet with them in person to discuss the grades. Any advice on handing students who argue about grades with grace?