Broken tooth after root canal

I went to dentist on main after a friend referred me to it in 2014. I had a tooth that was giving me problems after having had braces for the longest time. I get there and was helped by a friendly receptionist. I was told that I was going to need to have a root canal which I agreed to and they started immediately withe the procedure and I was told it's going to require me to come twice for the procedure to be completed I got authorisation from my medical aid (Polmed) the root canal treatment was completed that year. Now today I was eating breakfast and after chewing for the second time the same tooth the root canal was done on split into two while in my gum. The pain is excruciating. I believe that medical malpractice was done on my tooth cause to my knowledge a root canal treatment is done to ensure that a tooth is hardend from the inside out.