Iphone 6 touch screen not working and freezing a lot

I have an iphone 6, the screen freezes constantly and eventually stops working.

If I turn the screen off or restart it it's fine for about 1-2mins.

I have about 0.5cm crack in the top right hand corner.

Also have an appt with genuis bar on the weekend.

Does anyone know the replacement costs for the screen (i'm assuming they'll replace it due to the crack).

Thanks!