How do i return a mouse to petsmart?

So I got a mouse from petsmart yesterday to put with the 2 i already have and ive been keeping a close eye on her. She gets along well with the other 2 and she seems to be eating and drinking fine, but her breathing is rattly and she sneezes quite a bit, so im thinking she has a respiratory infection (i could be wrong) The store has a 14 day return policy but im curious if they would treat her and let me take her back, or if i would just have to get another mouse? And should i call first or just take her in and explain whats going on?
Answers

Quetzel

They may take a return but will not "treat it and return it" to you. They may exchange for a different one or return your money. IMO, if you're adamant about keeping it for its safety, you need to quarantine it away from the other mice and treat with a sulfa product (usually found in the bird section of the pet store) or Dri-Tail used for diarrhea for rodents. Either should work. Keep her warm, dry and well fed.

Love my Newf

You just take it back. But how stupid are you putting it with your other mice? What ever it has your other mice now have and they could end up DEAD!