Tree/bush blocking my right to light outside my window on mezzanine floor the bush/tree is on the ground floor and very close and tall and next to my window restricting right to light

Please ask Flat 2 at 76 Balcolmbe Street London NW1 6NE to remove and cut down the offending tree/bush that restricts my right to light and cannot open my window for fresh air as its right up to my window. They have cut a few branches over the last few months but now it has grown so big and I keep asking them to cut it and nobody does anything. Next door no 74 cut a few branches overhanging their garden but I cannot do anything as its grown outside the floor above where I live. Please ask them to cut this immediately please thank you. I tried to put through before on my account and will now have to anonmously as it would not accept I have a Westminster account but I do. Flat 6 76 Balcolmbe Street thank you.