I've had a look at your PCN status online.
Unfortunately it's reached Charge Certificate stage which means you've missed the boat for appealing. You could try explaining your postal issues to Redbridge to see if they'll let you settle this at a lower level (£65 or £130) but you may be stuck having to pay £195 or else it will only continue to increase. I don't know when the Charge Certificate was issued so I don't know how much time you have to even pay £195 so don't hang about.
Re the contravention, it does look to be made out in the video. You might have been able to argue the box extends a little beyond the junction but I think your odds of success would have been below 50%.
