Iphone case won't fit properly?

I have bought a gel iPhone 4 case that almost look like this but its not completely the same its just to give you an idea of what it looks like: http://killthemwithcuteness.com/jelly-belly-scented-iphone-5-

But the problem is that it won't fit on my iPhone 4s. Yes i know that you should prefereably not buy stuff thats not ment for your model of iphone but i couldnt find the right one. The case doesn't fit on the iphone 4s or my cousin's iphone 4 (on which the case is suppost to fit). You cab put the phone inside the case but the sides of the case don't cover the phone like its suppost to. Is there anything i can do make make it strech out or something to make it bigger? I know its a pretty weird question but i really need to know! (Remember its a flexible gel case)

The link is for an iPhone 5 case. The iPhone 5 has a slightly bigger screen at 4 inches compared to the iPhone 4/4S's 3.5 inch screen. That means the iPhone 5 is slightly taller and your iPhone 4S is too short to fully fit the case. Looks like you have to buy a new case.