Iphone battery replacement

Hello everyone, i just wanted some info on iphone battery repair.

My battery suddenly bulged out a bit. So, i shut down the phone and went to the repair shop almost after a month. Although today when i took the phone out of my drawer, the bulged out screen is more than what i saw previously.

So, when i went to the repair shop(apple certified repair shop), they told me that they can repair it but i have to take the risk of screen damage. Although the screen doesn't break, still if it does, it will be on me.

Now the point is, a screen repair will cost me around 25000 INR.

Is it legit that an apple certified store can say this?

I mean what if they intentionally break the screen?

Can someone please shed some light on this?