Turkish Airlines refuse to take responsibility for breaking luggage

I flew Turkish Airlines a month ago and received my luggage when I arrived but my bag was missing a wheel, my lock had been broken off and zip broken. I had bought this suitcase from K-Way the day before I left. Turkish Airlines firstly should never be handling customers luggage in such a rough way that a wheel breaks off, secondly, they took a month to respond to my complaint and thirdly they refuse to take responsibility for breaking my suitcase. Disgusting customer service and treatment of other peoples property.