England: 🏴󠁧󠁢󠁥󠁮󠁧󠁿 Land taken over how to respond to housing association

I took over a small patch of land next to my house which was over run with rubbish, grass and had a fridge for over a year on it. I meticulously cleaned it up and fenced it off to prevent people dumping rubbish. They don’t actually own the land however they want to have a meeting next Tuesday. In an email about 7 years ago they said that they do not own it. What can I do?