thanks for getting back to me, it started buzzing again last night, but it stops as soon as I move it slightly or put my hand on top of it, and it’s never buzzed since then. By the way the vents have never been obstructed, if I said that it must have been a mistake, sorry.
Cheers so much for popping back with an update @janeyh1959
Sounds like something may have become loose within the box to cause the buzzing noise. Are you ok with a self- installation of the box if we can arrange one to be posted in the next couple of days or would you require a technician visit?