OSM is a map, not a place for getting maintenance done. 

https://www.croydon.gov.uk/parking-streets-and-transport/streets-roads-and-pavements/rights-way says "We are responsible for ensuring that public rights of way are kept clear of obstructions and that landowners meet their responsibilities in this respect" so I think you could report the fence to the PROW department even if the fence belongs to the landowner.
