Is there a difference between an informal chat and a mediation?

[Emma]

I had a grievance with an employee regarding there attitude and it didn't get any better so i made a written complaint. We had someone come in who was recommended to the MD off one of his friends who came in to have an 'informal information gathering meeting', however during this meeting she told me i was in the wrong (even though i had made the complaint and had evidence to back it up) she told me that the other person was stressed and didn't even realise that she offended me. She also told me that the second person that has made a complaint about this employees attitude was 'caught in the middle and it was a issue between myself and the employee'.
I don't have any HR knowledge but i thought the 'mediator' wasn't to discuss what anyone else had said and not give her opinion on the matter, she also told me what the outcome wouldn't be if i make it 'formal'.

I just need someone to tell me if what she was doing was the right thing and can i make a complaint about her?