Issue with the battery thats still warranty

I have bought a battery for my car from Battery Centre Florida, after about a year, i have started having issues with the batter getting low, i have tried so many times to recharge it but with no luck, i have then went back to Baterry Centre Florida where i bought it, i have asked them to swap it out for me since it was still under warranty but Kobus told me that as per the policy, he cannot swap it unless the battery is dead, I have then take the car to BMW to check if there is nothing wrong with car that might be draining the battery but they told me that the battery needs replacement. BMW charged me R1000 for diagnostics and i also get charged for charging my battery with the battery shop. Can the batter please be swapped since it's still under warranty.