Mitsubishi Heavy Industries Ltd — 3 time installation a/c 1time change compressor but a/c is not cooling well

Dear sir,
I have purchased Mitsubishi heavy industries a/c on dt.4/3/21 harshil electronics bapunagar ahmedabad-24.we have a 3 time installation a/c & 1 time change compressor but not getting cooling well.we call many time to delars of a/c but we can not getting satisfaction. It is a company policy