purchase a portable boombox and set it up above your fenceline and facing in towards the nuisances pergola, visit your local music store and buy vintage cd's ofthe likes of, demis rousos, nana miskouri and englebert humperdink etc etc, then simply return fire nonstop!.
after a few weeks they should get the message.
ps: for a sound nights sleep dont forget the earplugs for your family members while undertaking this antiterrorist exercise.
