Jean tore within hours and manager does not want to exchange

On Saturday 11 May 2019 at around 12:00, I bought a jean at Zara. I put it on and at around 16:00 that same day the jean tore. I went back to Zara Tygervalley on Sunday 12 May 2019 to give the jean back. I think it is unacceptable that a jean (which cost me R 600) can tear within a few hours and I have bought a lot of jeans at Zara and none of them were this bad quality. I tried to give the jean back but the manager said I wore the jean and she will not take it back and I have app**** force to the jean?? 1. Yes - i have worn the jean, for ONLY 4 hours and 2. it is the worst quality if a jean tears within a few hours. I bought a jean at Zara (which is NOT cheap) because I thought their quality is good. However, I will never buy at a Zara again and the manager is down right pathetic. Now I don't have a jean and I lost R 600 which I think is a lot of money. Really dissapointed in Zara!