Hello everyone. I have complex PTSD and I have talked about this with my therapist.
First of all, it is OK to acknowledge that the neighbours are annoying. Horrible people even. However, annoying doesn't equal "fear". So if you feel real fear then this may relate to your past where you felt threatened as a child and you feared abandonment or death. Your body remembers this and each time your horrid neighbours make a noise your mind/body remembers your childhood and you are right back there. So the fear itself is related to a past incident or incidents. How do you resolve this? Well I'm still working on it, but there is a technique called Dual Awareness where you acknowledge the fear, and at the same time you look around at where you are, so you bring yourself into the present, and you tell yourself you are safe and are not going to die.
Also Boots do a earplug that keeps water and noise out. These will keep almost all noise out. Wear them when things get too much. Good luck my dear friends.