How to fix a small crack on iphone?

I bought an iphone 5s in november and its been dropped two or three times but it works great! However now there's a really small crack on the back side where the camera is. I'm thinking of going to the store i got it from and telling them it lags and doesn't work properly. ( i did that with my old iphone 4 and they gave me a new one) BUT - they're going to look for scratches (it doesn't have any) and cracks and when they see that they won't accept it. What can i do to cover the crack so its almost invisible? I'll need something to fill the little cleft and if i can't - can i put some moment glue so the small pieces don't fall?

Don't ask us to help you commit fraud.

Replace the back cover

Don't try to glue it together go to the mall or nearest phone repair shop they will fix the crack you will still kind of be able to see a little line if you look closely but for the most part it's invisable