From the L405 Aux. climate control Description & operation document:-
HEATER CIRCUIT
Supply and return coolant pipes connect the engine cooling system to the
heater core pipes of the auxiliary climate control assembly in the left rear
wheel arch, behind the wheel arch liner.
The coolant pipes consist of sections of insulated rigid pipes connected
together with flexible hose joints. Quick release fittings connect the coolant
pipes to the engine cooling system.
From the auxiliary climate control assembly, the coolant pipes are routed
along the rear cross member and then forward under the right edge of the
floorpan to the chassis longitudinal at the rear of the right front wheel arch
liner.
This connection is the forward part of item 1, which connects to item 14 on the previous location diagram.
In my opinion, they either don't know what they're doing or need to make up some cashflow shortfall - at your expense.