Unfair treatment by miway car insurance

Treatment I received from miway after my car got bumped....I'm so disappointed...my car overheated after I got bumped by another car even though it wasn't a major damage but my car started acting up immediately after the accident...but miway car assessor told me that overheating of my car wasn't due to my car being bumped....it was a long outstanding problem but my argument is I never had any problem with my car until the day I got bumped....so they couldn't give me the service I had to find my own mechanic to fix my car but I'm paying my insurance every month...I'm very disappointed and disgusted with their assessor cause he was using assumptions on my car...miway promised me service if my car get involved in an accident but at the end I got the slap on my face...Please Peter help me.