Apple engineer team refuses to replace phone, still under warranty

I recently sent my phone in for repair after I had problems with the wi fi and home button, my speaker also cuts in and out and works when it wants too, i purchased the phone new from best buy last october, i still have a few months left on my 1 year warranty, i was fine with the phone but recently the battery stopped charging to 100% so i decided to get it fixed obvious hardware issue? seemed apparent to me, well they received my phone 7/16/2015 and denied my warranty first saying i modified my rear case ,called and spoke to an senior advisor and explained my job and its environment and im often at times up 6-10 ft repairing landing gears, instead of taking a risk and letting the phone drop i often leave it in my tool bag, so i have scratches on my cover but always had a screen protector on the front , i chalked it up as normal wear and tear, i explained to the senior advisor , she said there might be an exception if an engineer approves of it , get a call back and said engineers denied it due to physical damage and its beyond economical repair ! what?! called back talk to another senior advisor they said they can submit another request because they understand the wear and tear statement i told them about, i explained my phone was working fine with the scratches on the rear housing, prior to the battery dieing and the phone not charging , i simply sent it in when it would not turn on anymore! that is an hardware issue ! senior advisor said she would contact me the end of the day its been 3 days! nothing chatted a few times with apple and was wondering if somehow i could contact and engineering team, i love apple but this seems to be the last straw.

Case ID: 839177010

iPhone 5

serial # C36KMBG7FH19