When logging in to reply I saw that the OP wrote their query two years ago so I suspect the matter has been resolved one way or another.
However, one person’s reasonable noise is another person’s unreasonable noise. By way of example a few years ago I had some plumbing work done (replacement water heater) and my adjoining neighbour declared there was lots of noise from the pipes. Had water hammer devices installed and ended up having three different plumbers come to try and find the fault. It cost me about $1500 to try and remedy the noise issue.
No source of noise was found and each of the plumbers said that any pipe noise heard in the adjoining unit was very quiet. Basically with 50 year old pipes there is a little noise. The neighbour’s story fell apart when they changed their story and said I had been very noisy one weekend I wasn’t at home. Then there were also instances of me not using water at times they said I did. I’d kept a diary of times I used water after 10pm.
When the neighbour sold up and moved up I went back to normal use and after a few months asked my new neigbours actually commented how quiet I was, There was the occasional pipe noise but it was underneath their unit so they would deal with it in their own good time.
One of the plumbers had told me that they thought the original neighbour was very sensitive to any noise and complained about what anybody else would consider normal.