Indigo Airline - My new suitcase was broken by airlines

I travelled with Indigo flight from Delhi - Chennai on May *th. My flight no. was *E - **** and my airline PNR was ZNMQYH. My new suitcase was broken by the airlines and when I approached the ground staff, he said "It happens" and please "Learn to travel properly". When I started questing him he offered me a **** Rupees voucher and said our airline is the biggest airline and you take it or go to hell.
As my suitcase is of hard plastic the part which has broken is creating a big crack in my suitcase and it is just a matter of time in which it will become a useless piece. I bought it from Tokyo just under a month back to which he said to go there and use it sir not in India.
On Indigo complaint chat I reported the same incident and they also called me and said: "Don't worry it will be resolved soon". Its been over * days and I have not heard from them.
Indigo staff was extremely rude and blunt and no consideration for passengers. He said twice that we are a large airline and what can you do let's see. Extremely bad and not in good taste.
I just want my suitcase to be repaired and nothing more. I have attached the invoice of the suitcase and broken image as well.