Fiona (not me) wrote in comments below her video that she thought of suing for harassment but the solution for her was to move away. The neighbour who complained is a music teacher but doesn't play any music at home and apparently says musicians should practice in studios. Fiona wrote in a reply to Peter Straffer on 8 May:

"the fact that they define it as 'any noise that can be heard' is a clear misinterpretation of a very vague law.

"I was going to appeal, but after considering the time and financial investment, the burden of proof being on me not the other way round (the 'expert' they'd consult would be the EHO) plus the fact that I'd be unable to practice in the meantime, and living with some very malicious neighbours, the safest thing was to move.

But I do want to make sure this doesn't happen to anyone else."
----------------------------
Fiona doesn't say whether or not she is a union member
----------------------------
There were a few comments on the Change petition site from other people who also had problems with complaints from neighbours re their playing music. And on the youtube page, a music teacher makes a comment that some of her students have similar difficulties: "occasionally when a pupil says they are unable to practise at home because of complaints from neighbours my heart truly sinks."