Yeah I've heard a case in my country where a young student suicided using pesticide.
The student ended up dead anyways but the process of dying can be described as "agony". It took around 20 days for him to die, laying on hospital bed, the chemical destroyed his body organs internally day by day, little by little, at that time the doctors had no cure for it, although they've tried their best but couldn't save him. The thing about this pesticide poisoning is although painful but most of the time, the patient was fully aware and can even talk with people, unlike various methods where the person fall unconscious after a specific amount of time.
Some people on this forum bashs SN method, but seriously SN is a blessing to the method above. Even cyanide is a blessing compares to that method.