Sodding smoke alarms that wait until 3:45 am to tell you their battery needs replacing.
I can top that!
Special phones for vulnerable people designed to send emergency messages...
My very frail elderly parents had such a phone installed. They wore lanyards round their necks with remote emergency call buttons attached. When pressed a button would cause the phone to repeatedly call round a set of numbers until somebody responded and then tell them that help was needed.
Late one night, the alert was activated. My brother-in-law heard his phone ring and leapt out of bed to answer it. He heard a message saying that Mr. and Mrs J needed help. He got on his bike, cycled round to their house, and let himself in with his spare key. As soon as he went in he heard a recorded voice emanating from the emergency phone. "
The batteries in this device need replacing". Over and over again.
My parents had gone to bed but had been woken up in terror hours later by the sound of intruders talking downstairs. They pressed the emergency button...