u/Kafkannasi

I live close to a bigger city in a semi rural area, in a traffic calmed area, so it is calm and quiet. I share a garden with nice neighbors. I love insects and birds and I have a bird feeder. About a month ago they installed an "ultrasound bird repeller", which is not ultrasound, because I can hear it. Constantly. The birds are still coming, it doesnt affect them but the frequent noise annoys the shit out of me. It is not loud its just constant and after I asked them to remove it, they made it more quiet, but its still there! It drives me crazy and I even offered them to clean their terrace, because they said they have it, because they dont want bird poop on it. But they refuse to put it down. I could scream. How do I ask them nicely AGAIN to turn it off? I like my neighbors, but I cant handle the sound anymore.