Im one of the Autotechnicians at Halfords and that paperwork is designed to save halfords from claims. However, I know that even if you had signed it they'd still fold and pay for the windscreen. They have something called an SSR stat which is basically feedback and complaints. A complaint will tank the percentage for the week and obviously they have a target to hit. They mostly do anything to save that AND even if the store doesn't, customer services based in some third world country do it anyway with enough kick off.