All the pipework in this area is also really loose.
I'm just going to cut out everything and completely redo the whole area with a new straight run in the corner, a new stop tap and a water hammer arrestor just for good measure.
I have also noticed that we are getting vibrations and small bangs in this area, when our neighbours are using their water.
I would too! Tidy it all up and put in a new stopcock with drain cock. Clip everything with Munson rings if you need it away from the wall.
You won't be able to deal with loose pipework in your neighbour's property though! Are you on a shared main? Sounds like it!