Over grown trees blocking light from street light

Trees from number 20's private garden have grown up and around the street light (located opposite number 4 Finham Brook) and therefore is not able to light the footpath or road. Tenet of the house has been asked to have the trees cut back at the start of summer and again since but has taken no action. with the darker nights this has become a more of a worry. Also due to this a fixed bollard in the footpath has be knocked over and now there is a hole in the footpath which is also not lit!