I make it that you were in the bus lane for 17 metres. This would ordinarily be considered de minimis at London Tribunals, but it's not a guaranteed win, I'm afraid. You must emphasise that no advantage was taken of other road users as the video shows.
Needless to say the council will reject your reps because they only want your money, there is no traffic management purpose in enforcing such trivial offences. Indeed they are being as mendacious as the possible can by not showing the end of the bus lane in the video. The end is actually the sign in the video that you can see the back of at the bottom of the camera view.