Hi there @janeyh1959
Thanks for popping back - I am sorry that your box is now making a buzzing noise after the visit you had a couple of weeks ago.
I am just doing a few checks on the box from this end for you. We can see it's been around 3 days since the last reboot - how's things been looking since your post?
You also also advise in your reply that the vents are obstructed - have you managed to clear these at all and has that helped?
If you are still having the buzzing noise after these have been done, let us know and we'll see if we can either arrange a box swap if you are happy to self install, or a technician if not.
Cheers