Honestly if someone tells you they do chelation and their patients have not had any problems, run--away.
People who need chelation are so often very sickly with a long list of symptoms. Hg makes it more difficult for the body to get rid of other toxins and testing for the situation is difficult--the toxins tend to stick to vulnerable parts of the body, not float around in blood or urine.
With chelation there are usually bumps in the road, people who have a long list of symptoms could expect more bumps in the early months. Furthermore it is not easy to predict what doses of which chelators a person will tolerate.
It takes a long time to get inorganic Hg out of the brain. Be alert for salesmen.