Mitsubishi Electric India — Improper installation

Address:

Chennai, mobile 9840044287

I got my new Mitsubishi 1.0 ton split AC installed today 18 th June 2021.
I was at office when it was installed.
Came back home was totally upset on seeing the indoor unit. There was gap of half an inch through which I can insert the fingers between the wall and indoor unit . This was looking ugly and the unit vibrates when working. Tried contacting the office and technician but they are giving me vague reasons