I bought BMW Battery I was given warranty it start to give me problems I took it back They re charge it

I bought BMW Battery I was given warranty it start to give me problems I took it back They re charge it. The next day done the same I went back to them they check it with their machine it say Replace Battery I was told they send it for exchange is now almost a month I have done follow up today Now Mufuro is telling me that they won't replace my battery coz there is little dent on my battery poles I ask him him is that little dent coursed battery to die he can't answer I think they are trying to find little accuse not to replace ppls Batteries