Difficulty replacing a damaged cable

[Lectrician]

That's how I am reading it now - I assumed it was a bungalow, first floor kitchen or some kind of single storey extension. If the kitchen is on the ground floor, you will not be able to locate and pull the cables in the loft above the floor above!

Even if the walls are on top of each other (and they don't sound like they are), the cables are unlikely to go from ground floor, through the first floor and to the loft in one non stop piece of capping or conduit.

Where is the wiring centre for your central heating - can you relocate the programmer to there instead, or close to it?

 

[Taymar]

It's a GF kitchen with the bathroom above, then the attic.

The cables go straight (it appears) up to the attic, then go across the floor to above where the airing cupboard is located where they drop down.

As one last effort, we tried to pull up both cables together, but still no movement. The best solution now (given the advice given here) seems to be to use the junction box in the attic, quite near to where the cables drop to the airing cupboard. Then, we'll drop the cables down to the landing and relocate the HW/CH controller there.