Pedestrian crossing times out

The main pedestrian crossing on the College side of the road has an issue where pressing the button to cross seems to time out. You press the button to cross and the red light appears on the pedestrian signal to indicate it's been requested. You wait ages and then the red light goes off, but you don't get a green man and the traffic signals don't change. You have to press it again to try again and wait even longer. It's been this way for months - really annoying and also potentially quite unsafe