Pegasus Luggage Damage

I flew with Pegasus Airlines on flight PC977 from Sabiha Gökçen (SAW) to Berlin (BER). When I received my checked suitcase after the flight, I saw that the zipper puller had been ripped out in such a way that the zipper can no longer be used at all, which makes the suitcase practically unusable. This was a new suitcase that I bought only a few months ago for 75 USD, and it was in good condition before the flight. I submitted a damage claim to Pegasus, but my claim was closed with a standard response stating that Pegasus does not accept responsibility for damage to wheels, handles, straps or zips, citing their procedures and website. I find this unacceptable, because this is not a minor cosmetic defect but damage that prevents the suitcase from being used as intended. I request that Pegasus provide an appropriate solution for this damage, preferably a refund of the 75 USD purchase price or a repair or replacement of the suitcase so that I am not left with the full cost of damage that occurred while the luggage was under the airline’s responsibility.