Fused spur connection unit in bathroom with no power

[Gramercy]

Hi, I have a 13a fused spur connection unit supplying a bathroom heater as pictured, which is no longer working.

I tried replacing the fuse. I tried tightened the wires in the unit thinking maybe one had somehow become loose, no luck. I was going to simply buy a replacement unit but after using a non-contact voltage tester.........apparently there's no electricity going to the unit at all - am i right to think the tester would still recognise the live supply even if all the wires aren't connected?

Is this is something which requires a professional or is there something i've missed trying?

Thanks

 

[chivers67]

Where is the Fused spare / FCU fed from ?

 

[Gramercy]

I'm a complete novice so i'm not sure, but there's another fused connection to the left which i think supplies this unit and the fan, light etc. The attached photos show the two units and the other units directly on the other side outside the bathroom.