I have long standing problems with a neighbour whose older house is above and to the side of my rear garden. It was fine until he moved in as the previous owners obviously tended their garden but I have had years of severe ingress of plants from next door reaching into my garden by as much as ten feet. Periodically he has chopped them down at the root on his side allowing the mass to drop into my garden below so I've had masses of ivy, climbing rose and other plants all falling down into my garden and he has refused to clear it up, becoming abusive and unpleasant. When his fence rotted he even put up another one on his side of it and left the rotten one for me to have to take down and dispose of, so moving the boundary in the process.
It has been a stressful few years and I have done all I can to avoid directly addressing his behaviour. Two years ago his garden began collapsing into mine and he came over several times demanding that I do something about it. I called my insurers and they sent a civil engineer who told me it was very much the neighbours problem to resolve, his fence, his plants.
Inevitably he came to my home a couple months ago wanting to know what steps I was taking and I told him it wasn't my problem but I was prepared to help where remedial action was concerned. So he has employed someone and a new wall and fence have been constructed along the side of his garden adjoining my own and I contributed a substantial amount of money while also allowing the work to be carried out from my side. Only a week later I now find the end of his garden is also subsiding and I let him know that his garden wall was hanging unsupported and dangerous as it has no foundation. He came around and was his usual bullying self telling me I needed to pay toward holding it up.
I have reached my tipping point. It has cost me around £2k sorting out his mess over the years and I'm done with him acting as if I owe him and he's doing me a favour. He proposes tipping concrete onto loose earth to hold up his wall - I'm no engineer but surely that is not a permanent and safe fix, so I have told him I want no part of it. He now asks will I allow him access to my garden so he can put the concrete in place. I want to tell him no. Am I being unreasonable?