Wolfgang Fartbubble wrote:
He has approached the neighbour but he wont have any of it and simply
will not listen.

In the majority of the world (including the US and the UK) the 2.4GHz
ISM band is available for wireless use by unlicensed users on a
secondary basis. That means that wireless users may not interfere with
others, and must tolerate any interference received.

In this case the licensed neighbor is under no legal obligation to do
anything to correct the interference.