Is it legal for a bank to take money from my mom and dad's account to cover a negative balance on mine>?

Long story very short, my bank implemented overdraft protection on my account without my knowledge or consent, and because of that, and the fact that my online statement was wrong, I ended up spending money that wasn't there and racking up over $400 in overdraft fees.

I've been trying to figure out if I can take legal action or if I could come up with the money somehow, but in the meantime this happened: My mom is on my account with me. She also has another account with that bank, and my dad is on that account with her. Today, without any warning, letter, or phone call, the bank wiped out her savings and checkings from her and my dad's account to cover some of my negative balance, and then sent my balance to collections.

Is it legal for them to take her money from another account like that, without even telling her?? Any advice would be appreciated. Thanks