Horrible Service

I bought underwear on the 25-06-2019 on the buy one get one free i normally buy my underwear at Kurt Geiger but coming to my surprise the other one the elastic didn’t even last 2 hours this was a total day light *******.i went back to the store to explain to them about all this but they told me something that i know that underwear’s are not returned but now this is so different because this is a factory fault.Can someone urgently assist since the store consultants promised to give feedback to me this items where bought from Clear water Mall urgent feedback please