Thanks for your post and welcome to the forums. Sorry that our website wasn't clear on reporting the broken cabinet near you.
As per goslow's post we do have a dedicated page where you can report this to us, or alternatively, if you don't feel comfortable writing this location for others to see then please feel free to drop me a private message.
I'd just need to know:
Where the cabinet is; providing a street name and post code and nearest building number is great - pointing out any landmarks or junctions nearby will help us ensure we're reporting the correct cabinet)
If you are referring to the page that has been recommended above by goslow then there is no button that you need to press. To add a comment you can just scroll to the bottom of the page and the 'Post a comment box' is there to type in 🙂