@strawberryshortcake1
Thank you for the picture, it helps to make a lot of sense of the situation. (always love a photo and plan)
There are a number of ways to approach this.
We have been here since 2017, we have since found out the previous two residents had problems too. I cannot emphasise enough how verbally aggressive, him physically aggressive, manipulative, narcissistic and gaslighting they are.
Frankly, unless this is your absolute dream house (although with neighbours like that I doubt it) then my advice would be just to sell up and get the hell out of there. Life is too short to put up with neighbours from hell like you describe.
I have no idea what the letters you mentioned refer to but it does seem very odd indeed that they are claiming adverse possession.
If I understand this correctly there is a bank between the two properties which is the boundary. They have been dumping their rubbish over the bank onto your property and claim that this gives them adverse possession of the part of your property that they have been dumping rubbish on. Is this correct?
If this is the case then this is absolutely absurd. Dumping your rubbish on somebody else's land does not give you possession of it. It is actually an offence - fly tipping. Both the local authority and the Environment Agency have powers to tackle fly-tipping and if you want to go head to head with your neighbour then tell them that you will be reporting them for fly-tipping.
You purchased the property in 2017 and there have been a couple of other owners in the, presumably, recent past. Your property will definitely be registered and if the neighbours ever try to make a claim for adverse possession then HM Land Registry will contact you to see if you object. You will have 13 weeks in which to register your objection.
Even if they had fenced in that section of your garden they would have needed to do this, and have evidence of doing it, for at least ten years and done something to prevent you and the previous owners from using that part of your garden.
From your description, that has not happened and they appear to have no basis for what they are claiming.
Personally, I would suggest:-
- Move
- Move
- If you really don't want to move away then consider putting up a 2 metre fence on top of the bank along the line of the boundary to lessen any contact with your neighbour.