Apple giving me the run around until my warranty is done. HELP!

My Macbook 12 inch 2015 battery depletes 50% after 2 hr use, no bluetooth or other programs running, while uploading and editing pictures. Apple support tells me my battery is borderline defective, Apple store tells me it's a good battery. Sent it in to have it assessed by Apple and told it has 7.5 hr battery life playing videos. I cant's even steam for 1 hour before it depletes 50%. Now Apple care is done and forced to either have to live with defective battery or buy new one. HELP!