Ebay App Problems- General Phone Issues

Hello! I am having Ebay (and only Ebay, it seems) app problems since I got this phone. It decides to notify me of ending auctions 5 minutes after it is over or mostly, not at all. I've troubleshooted the app, uninstalled/reinstalled, made sure notifications are one, etc. If I could go back and exchange it, I completely would. It's a fantastic paper weight. I am blowing through my data as well because my WiFi is slow in all places (home, work, Starbucks, you name it). I had a Note 2 that worked flawlessly. Beyond the Ebay problems my battery life is complete crap (which I see is a general Lollipop problem). Verizon gave me a new SIM card and it has done nothing. I am mainly concerned about my Ebay but any other help would be much appreciated. If I didn't owe about $600 on it, I'd sell it- it's that bad.