<human>: So like the title says, my dad took away a really expensive watch of mine as punishment for getting bad grades. I had a big test in one of my classes and ended up getting a B on it. I have to show all my test grades to my parents, so he got pretty mad when I came home with the B on my recent test. As part of my punishment, he went into my room when I wasn't home and took a really expensive watch from me. He says he will give it back at the end of the school year. This is my favorite watch and prized possession. Something I use/look at every day. He just went into my room and took it without me knowing. I can't wait months for him to give me my watch back, and don't think that it's okay for him to just take my stuff as punishment. He has also taken some of my nice clothes(that I really need) and says that I need to focus on school and not what I'm wearing. 
How can I explain to him that it's not okay for him to just take my things and that I'd be more than happy to deal with whatever punishment he has in mind?

Thought I'd add some details, not sure how relevant they are. I am a freshman in college, will be 16 in a few weeks. I wanted to live in the dorms, but my dad convinced me to save money and live at home. He told me he would respect my privacy and my room as my own area and not go in it. 
Also since lots of people are asking, he did not buy me the watch or the clothing. He does not have much money, and I bought them myself. I would have absolutely no issue with him punishing me by taking away something he bought for me. I just don't think it's a fair punishment for him to take way things I worked hard for and bought with my own money. I don't think the punishment fits the "crime" He doesn't seem to understand that college is a lot harder than high school and that I'm not going to get an A on everything. In fact, my teacher was more than happy with my B and said that it was a great grade.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Got a bad grade on a test. Dad went into my room when I wasn't home and took my 15k watch as punishment.