Firstly, I’m sorry for your loss.
Secondly, please ignore the ‘helpful’ advice to put notes through their door and similar nonsense. The situation is already resolved - you’ve spoken to the police, they’re satisfied you’ve done nothing wrong; there’s nothing more to do. These neighbours don’t want to be your friend, and if it was them, presumably you don’t want to be friends with them either. Why create unnecessary confrontation?
if they had bothered to talk to any of ours and their new neighbours would never have happened
To be honest, this sounds a bit like ‘If only they’d just fit in and be like us’. You made them saying they didn’t need a recommendation for a butcher’s sound like a major snub. They could be vegetarian for all you know!
They can’t turn back the clock and become more friendly from day one... so my question is, if they had come over and asked about the cars, would you have been glad the misunderstanding was cleared up and moved on? Or would you have been writing a different AIBU, asking if you’re justified in feeling pissed off because, having never spoken to you before, the first time they did was to complain about the cars?
They’re not your sort of people, which seems to be their main crime here. Forget it, move on and enjoy having the friendships you do have with your other neighbours.