OK, so GSV shows there are two NRT signs, one each side of the exit into Shaftesbury Avenue. However this GSV view shows how signs can become obscured, although one is visible, plus there is the "Turn Left" on the carriageway.
https://maps.app.goo.gl/ranm6uH1y8CdTmgD7However, the video shows the street clear of parked vehicles near the junction, so I have to reluctantly say that you don't appear to any solid grounds for cancellation of the PCN as regards the location and its signs. It's possible there may be a 'technical' appeal based on Westminster Council mismamagement of the enforcement process. So wait until the "technicians" comment, but don't miss the deadline to pay or submit representations as indicated on the PCN.
