This one is solved but I'll post it here as a reference etc.
During the cold snap the Fabia's screenwash jets froze, no surprise as I was caught without a fill of winter mix. However, after the thaw, still no joy. Probably fused it by working it against the ice.
Fuse diagram says fuse 46 in the internal (driver's footwell) box is front and rear window washer, operating lever under the steering wheel. Pulled that but it's intact and a continuity check confirms it's passing current.
POst on Briskoda suggests checking 22, 27 and 31 as well. Pulled 22 and a possible Bingo moment; that's blown. Manual says it's front and rear windscreen wiper system but 27 is specifically allocated to the rear wiper and 8 in the under bonnet fusebox is also wiper specific.
One or two other bits of the handbook are poorly translated, maybe this is another example.
The fuse is a tiny little 7.5amp job and nothing in my kit(s) matches however there was a 10amp in the Berlingo's spare bulb etc kit of the same profile. Pushed that in and all is good.
It will do as a temporary measure and Mrs B will pop into Halfords for a 7.5 amp one later - we cannot both be out as a delivery is expected.
If your 16 Fabia has the same DNA as our 16 Octavia and 14 Yeti, the fuse possibly blew after an attempt to trigger the rear washer rather than the front. The front screen washers only pump for as long as the stalk is pulled, but the rear screen washers are programmed to spray for a whole second no matter how briefly the stalk is pushed. Headlamp washers, if fitted, are also programmed to spray for a set period of time (2 1-second sprays on the Octavia, one on the Yeti), hence the proliferation of control units and fuses!