Ceiling speaker dislodged


The Tannoy ceiling speaker in our office has become dislodged. This happened before my arrival to the office so I'm unsure of what cause the issue; however I have been asked to solve the problem! It doesn't push in or twist into place- is there instructions somehwere on how to secure the speaker again? Or perhaps contact details for someone who could fix the problem? The office is based in Soho, London 

Many thanks