The bike has been bought from eBay so having the shop repair it is not possible.
Its possible but you have to pay the shop out of pocket..
Installed with smooth arcs and appropriate lengths in lined housing with die slicked cables is minimal drag .
SIS housing needs special Cutters , and is best, if after cutting, the ends squared up on a bench grinder.
before slipping the ferrules over the ends.
for a foul weather bike, the continuous housing resists contamination , you will be fitting mudguards next, Right?