Youd have to be walked on to "prevent" being walked on.
You have to deskwarm, oh no!, Read a book, you don't have to teach classes, you're not being asked to teach more classes or anything, so you're not being walked on. You also have no proof that this decision has to do with you not re-signing, you know Korea a parent could have complained that you went on the last one or something and they told you last minute ( much like you did)
You have to gives tests some days for 6 hours, and others for 2, um yeah? but in the end the number of total tests doesn't change right? So your complaint is that on some days its too much, on other days it's too little? Are you going to go to a bear's house after that and start trying out the chairs, the porridge and the beds

I am always baffled by the teachers that say they are being treated unfairly or walked and regale us with tales of " I have to deskwarm" You may have a feeling the VP is doing something with abosultely no evidence that he is.
So what can you do, finish your contract and go home. Before you do that though, try putting things into perspective and loosen the heck up. You're leaving, I don't think they expect you to teach there till you retire. The average teacher stays at a Public School job for about 16 months( I would guess) they got you for two years. Why do you think they would hate you for this?