@Tabiaat,
Overseas boarding school is probably super-expensive. It's certainly expensive to travel to you or for you to come home. They would see you less, too. Don't you think they would give a damn about that?
So you need to see things a bit from their perspective. Can you find an inexpensive school? Can you live at home and go to school? Just wanting to change schools isn't enough unless you're being actively bullied or denied an education. After all, what if you change schools and decide you want to change again?
If you can show them you can be responsible about this, then maybe they'll consider. But in the meantime, we all face unpleasant situations. Dealing with them positively and proactively, and without running away from them, is a mark of maturity.