Video shows you are in the bus lane which is very long, but there is a sign about 230 metre back : -
https://maps.app.goo.gl/rGGoeVZtxjt65NY38However their video shows your car turning left into an entry to premises just before the bus lane ends, here : -
https://maps.app.goo.gl/Zway8C9sEiADsLwA6So I would say this is a very trivial contravention and fits into the
de minimis category. From what I can see you did a normal traffic manoevre to turn into the premises, so I would submit representations on that basis. Havering are, unfortunately, exceedingly venal and rapacious, and will not re-offer the discount when they inevitably reject your reps.On the other hand, this means it becomes a total no-brainer to take them to London Tribunals where I would think you should win. Even if you lose, Havering will have had the fag of preparing an evidence pack and also will have had to pay the adjudication fee, so at least you'll force them to do some work for their ill-gotten gains. The plain fact of the matter is the PCN should never have been served for circumstances like yours.
It is either the above or join the Mugged Club and pay the discount.