I would recommend talking to apple over the phone ...

I would recommend talking to apple over the phone first before trying to come into the store. They will set you up with a guaranteed appointment and it makes everything much easier. I have an iphone 5s, the volume buttons stopped working and the screen has a delayed response time. I called customer care, they created a case and when I walked into the store to my appointment it was replaced right way. I save lots of time and while I waited a few minutes in the store I looked around at all the cool expensive products and accessories. The staff that I spoke with was very polite and helpful, hope this is good advice.