16yr old strict parents

I’m 16, I have relatively good grades, most above a 7 and a few 8s and 9s. I bought some subs online, it was a mistake and my parents found out. I threw it away, however they are punishing me for it. Bearing in mind these punishments have been going on for a month now, this is what they have done. They have taken all my passwords to my online banking and all my bank cards, I am not allowed to have any cash. They have taken my phone. I am not allowed to go anywhere or see any of my friends. I can only see my ones in school. They have cancelled my tractor driving test and they still shout at me about how my existence is a disappointment. They have taken all my passwords and I am not allowed out. I feel like I have no privacy and no access to my money which I earned. My mum says she will stop this when I give her the sinus I bought but I have gotten rid of it. I have a brother who is the same age who keeps lying to my mum and telling her I am being mean to him and he keeps telling her that I am still using snus. What should I do