Man I completely understand. I fucking HATE mental health services. They're just a bunch of drug-pushers, working for drug companies - and the only thing their drugs do is make you fat - and nothing else.
I know man. I know how you feel. I had a psychiatrist in a public mental health service, that could barely speak english, and when interviewing me he didn't even look at me. He stared at his computer screen. He read out a bunch of stupid meaningless questions, and put them into the computer, and the computer told him what medicines to prescribe me. He looked at me maybe 30 seconds during the hour long "interview".
I've been so pissed off at mental health services, that I didn't want to kill myself in front of their homes - I wanted to fucking burn down their homes.
But really it's not the worker's fault. They're just trying to work a job and make money and survive like everyone else. It's the corporations to blame, man. It's the power hungry pigs at the top living in mansions. There's literally nothing you can do about it on a personal level. The only thing that will stop this corrupt system is a revolt - a complete world-wide human revolt on society itself. That will never happen.
When you leave your note, just express how you feel and why you're doing it in your note, and why you think things are so corrupt. Eventually, there's gonna be enough death caused by this bullshit in our society, that maybe society will do something about it. Personally, I choose the same thing you're choosing - my personal revolt is a revolt on society, and life itself. I'm rebelling against life and everything it stands for, and I'm revolting by choosing death.
One last thought - If you leave a suicide note on social media, someone's gonna call the cops and they'll be knocking on your door in 30 minutes after you make that post if it's on a site like Facebook that has your personal information. Just keep that in mind.