i use TFR Traffic Film Remover all over my car, its faded anyway & has no shine so doesnt bother me,
it removes all polish,wax,oils,fuel,bugs,tar,silicons,grease,salt... etc etc whatever can be thrown up off other road users,
if you have nice shiny paintwork it will remove all of your polish etc so you will defo need to re wax the body work after its dried!
its a harsh way of removing all dirt put it in a trigger bottle & leave car dry! spray all over car windscreens bodywork alloys everything but DONT LET IT DRY add more & use a worn out scotch pad (sponge 1side corse on other ask your wife she prob washes up with them!) to clean windscreen/windows the wiper blades & alloys only!! use a jetwash & wash off all of car then rewash with your normal basics carwash with HOT water sponge like normal. That should do the job
next day polish bodywork! if required...
if not hammer & nail in the O/S section of screen in drivers vision ,just lightly tap it & it will chip&break then give it a smack or 3 with your palm to send a spider crack across screen or the screen replacement company may just repair chip & ull be back to square 1!!