Faulty battery that was bought 2025 June, they refuse to acknowledge its faulty

I bought a battery June 2025, its now March 2026, the battery is giving me problems. I took it back and was told there is nothing wrong with the battery, yet I have to jump start the car everything. It is definitely not the alternator, it was checked! I am sooooo disappointed at their level of service & shocked that they refusing to acknowledge that their battery is faulty!