iPhone 6S Plus 64GB - Battery issue

Hi,

I've recently bought an iPhone 6S Plus on a EE pay monthly contract.

After using it for a couple of days, I noticed that the battery drains MUCH quicker than my old iPhone 6.

So yesterday I turned both the WiFi and the 4G on and played HD videos on Netflix until the battery died (which didnt take that long either, about 4.5 hours).

There is a significant difference for the worse compared to the iPhone 6, which makes me think the battery is faulty. It also gets stuck while charging, say at 97%, then jumps to 99% after some time.

I'm thinking I should return the phone and get a replacement.

I've also attached a screenshot below, please see the time since last full charge.

Thanks,

Mike