Closed route

Rather annoyingly A cycle travel route led me down a private road that was closed off, today leaving me with either a lengthy detour or as scramble, with my road bike on a very steep muddy path (up to a busy main road). How do I report this part of a route being closed to the public? It was Titsey Place in Surrey. Really the only way north was thr devil of a hill, Chalk pit Lane, (which is what the circular route Cyclestreets had plotted for me, took me down)

the route is here

https://cycle.travel/map/journey/520164