What can I do?

Hello, does anyone know if a disabled facilities grant officer and occupational therapist have a say over a housing association? 
I live in a ground floor flat and prior to allocation my OT did tell my Housing association (Clarion) that I'd need wheelchair access and scooter storage.
The DFG officer from my local council has been out at my OT request and put forward plans to use the communal 'garden' it's actually a strip of ground that sits outside my back door, and install a ramp and scooter shed.

However, I have only two residents of 15 that say they want to use the communal garden for their children to play in so my housing association are looking to disallow the application (according to one of said residents who says my housing officer told her). 

 I've been allowed to use I as my own space for 18 months and have spent money turning it from cat litter shingle to a decked and flowered area. 

This 'communal garden' is directly outside my back door and I have m.e. & Fibromyalgia and am highly noise sensitive. I'm very concerned. My housing officer isn't responding to my request for a discussion about this. 

Is there anything I can do? Does the housing association have the power to veto the disabled access plans put forward via my OT and Disabled Facilities Grant Officer?

Anyone been through this or have input? 
Thanks and sorry for the long message.