So I'm 19, and my Mum is always opening my mail. Literally can't even remember the last time I saw a bank statement of mine. I've been having some investigations done at the hospital to do with my head and I had a letter today. She sent me a photo of it whilst I was at work, therefore she had opened it, despite the fact that it literally had "PRIVATE AND CONFIDENTIAL" written across the envelope.
Question is, how can I ask her to respect my privacy without it turning into an argument?