iphone 6s dies with 30-40% battery

I recently purchased a new iPhone6s (last October) and have been using it regularly while working out. Before this phone, I used a 5s, 4s, 3s, etc...and never had any issues, until now. My phone currently dies with anywhere from 30-40% left on the battery and apparently it is due to "water damage." I met with a Genius yesterday at an Apple Store in Portland (as I'm sure you know because all of this information is stored) and he informed me that my phone warranty was void because the water damage indicators had been triggered. For the record, I have NEVER dropped my phone in a sink, toilet, pool, bowl of soup, water glass, the ocean, or any other body of water (although for some reason, I received a report stating that the phone was damaged by "liquid damage from drop in tub" as well as a charge for $79 for "flat rate retail repair" and "iphone service fee"). I'm not sure what the asinine charges are in reference to, because I received neither any service or repair (also for the record, I wasn't charged anything in-store).

What I was told, was that it is entirely possible and likely, that sweat and or humidity from being in a case can trigger the water damage sensors. With that said, I find it ridiculous that this flaw is apparently acknowledged and basically ignored. The feeling I received from your Genius, was one that represented a "**** outta luck" or "well, sorry, we know about this, but we can't do anything for you." It was like a child was admitting to me that he knew he did something wrong, but didn't care about his wrongdoing. That is not the type of support I expect from a global leader in electronics and innovative products. In fact, I know you have some of the best engineers on the planet working and designing your products, just like Samsung has some of the best engineers working on theirs...apparently the Galaxy S5 has a completely waterproof version up to a certain depth/time. If they can make sure their product is waterproof, surely an iPhone can handle a bit of sweat from being at the gym (and no I'm not one of the gross people that is covered in their own slime from excessive perspiration). Given lifestyle that Apple aims to portray and the accessory products they make, it's almost as though they encourage you to work out with your phone. Although, maybe I'm wrong?

Now let me dive a little further for you. I have been a loyal Apple consumer for nearly 25 years. I played Oregon Trail on my Mac II in 1990, made my first surf film edit on iMovie from a first generation iMac in 2000, and now Face Time with friends across the globe with my iPad or iPhone. I've purchased every new generation iPhone, half a dozen i generation computers (including lap tops/airs), countless iPods/Pads, and even an Apple TV. I've experienced nothing but good service and product functionality, until now.

Given the circumstances, I would greatly appreciate a bit better answer than "well, we can swap out your phone for $329, or you can take it up with your wireless carrier and see what your insurance deductible is."