I have been trying to get RHP's to clean their own...

I have been trying to get RHP's to clean their own land in Twickenham for the last 3 months. They have not cleaned that land for more than 10 years.
I am very disappointed by the service that I have received as it showed lack of care and appreciation for their own land. The slow response process via email is also unacceptable, and when I give them a call, the relevant people are never around or have no update for me. It is so difficult to get any useful information and I can't imagine how long it will take for RHP to action things.