you won't need to pay - do what is proposed above, and make something hit it while you were on the motorway.... lol. hit it with a hammer, go back, and they won't be able to repair it, so will have to replace.
Well I tried this when my screen was repaired last month, granted not through Autoglass, and couldn't manage to swing it.
My understanding was that you would only get a genuine screen if one couldn't be procured from their usual supplier, as if often the case with very new models.
They will only replace the screen via insurance if it needs replacing, in this instance I was told it didnt... Im not happy with the repair so I will have to pay for it myself because the insurance wont.
Take your hairdryer to the spot where it was chipped and it will crack - they cannot repair and new screen is on its way. One thing you need to tell them is about the rain sensor which IIRC means they need to fit a Renault one for some bizzare reason, at least that is what I was told when I had the windscreen guy out.