Mine is fairly silent - did the engineer ensure that he had downloaded the latest software??
Have a look at this thread, it details the up-to-date software version and what to do if yours is not this version. To check which version you have just press the following on the SkyHD remote :
* Services
* System setup
* System details
Then look where it says "Operating system version"
I would reboot it anyway.
Cool rebooted that unit and things have settled down. Thanks