Incorrect car diagnosis

I am pretty upset, as i recently took my newly bought car to pass roadworthy. There were a few minor issues like tint on the lights that had worn off and needed to be replaced, etc, and then a few more serious ones. One of these was that the right front strut mount was apparently worn (originally written the left, and then scratched out), and needed to be sorted. I EVEN got my mechanic to call in and speak to the guy to ensure that he understood exactly what was wrong. We then proceded to buy the part needed, and fix accordingly. My mechanic took everything apart, and said that he cannot fault the shock mount, nor any part of the shock. Not only had I wasted time and effort, i had bought a part that has no use, and paid for labour, on something that needs no replacing. Now I run the risk still of it failing still for something that has nothing wrong with it. <br> <br> I really dont know what to do at this point, as I am supposed to have these \issues"all sorted by December 2nd."""