Hello, advice needed concerning a Penalty Charge Notice received for parking

[freedom5791]

Hi, Ive recently visited a friends house in Bracknell, there isnt much parking on the road but there is a garaged area with enough open air space for about 4 or 5 cars to park without obstructing any of the garages. It was a friends birthday so there was 4 cars parked there including mine and they were left overnight. When I returned to the car in the morning, all 4 cars had PCN notices on there windscreen and 'NO PARKING' signs had been fitted which werent there before. Also on the PCN it states that photographic evidence of the offence was available via a QR code within 24 hours of the notice yet 7 days on now and the QR code still directs me to a link that says 'page not available' . Obviously, like anyone I dont want to pay it, but I also feel its unfair that they expect me to pay but I have no way to prove the signs werent there before. What can I do?

[freedom5791]

I have just asked my friend to send me a pic of the sign they put up in case that helps, and ive scanned a copy of the pcn