What is the process of swapping an iPhone 6s for another one in store when on the upgrade program?

So I have an iPhone 6s on the Apple Upgrade Program. I'm within my return period. I want to take it back to the apple store and have it exchanged for another one because I believe my battery is defective. It's behavior is not consistent with anyone else's i've seen, it is draining incredibly quick with very few background refresh apps on and not heavy usage. (for example the other night it hit 20% and I put it on low power mode. in less than an hour - probably 30-40 mins - it had dropped to 15% just sitting in my pocket. again on LOW POWER MODE.)

So what is the process? Will they just scan mine back in and scan me a new one and that's it? Or will they have to cancel out the whole financing agreement, refund my money, and then start the process all over again, re-checking my credit and all that? I'm sure some of you have done this for the whole Samsung to TSMC swap, so I'm wondering what the experience is.

Thanks!

edit - and I'm on Verizon if it makes a difference.

 

well all i know is that i have a new phone within the 2 week period, i'm not happy with it and i'd like a replacement. however they want to do that is fine with me but i'm not gonna wait for the genius bar or anything like that. since it's a new phone it should all happen through the sales department in my opinion and not through tech support.

 

they wouldn't be able to do an exchange rather than doing the whole refund and payment process again? i have no problem bringing the box and all that, i just don't wanna deal with the credit check again and all that.