Mitsubishi Electric India — Non replacement of defective AC within warranty

Purchased six AC units for my home. Moved into the house on 30 June 2023.
One AC did not cool from the beginning. Repeated visits by service centre personnel. Filling up of gas. Checking of pipes/ ducting. Laying the blame on the builder for ducting which was found to be leak proof. Finally AC unit taken to the centre and accepted as faulty.
The dealer and the service centre now insisting on fitting the same unit citing company policy. The unit has been defective from the beginning, within warranty and needs to be replaced by the company.
I have suffered denial of service for one month in peak of summer, frequent disturbance by visits for repair and consequent stress. Ongoing delay will only add to the stress and costs.