850 Heater Hose/Matrix Junction

[Joseph Martin]

After having a wet passenger carpet for long enough, I now have the time to begin sourcing the cause. I assumed heater matrix failure, and the staining on the sound deadening and matrix box seems to confirm this. However it didn’t seem likely that the sound deadening, which was soaking, would just be wet from here. And so when I investigated further, I found that the pipes down towards the heater matrix are dripping wet, almost like condensation, but these are notably dripping water, and the sound deadening, which is foam backed, is absolutely soaking wet.
I’ve been looking and wondering if the heater matrix junction, which is where the coolant pipes pass through the bulkhead and into the cabin, is perhaps the culprit. The pipes from engine to junction under the bonnet were replaced a couple of years ago (not by me), and I wonder if it has disturbed this.

Either way, it’s either going to be the seals or the heater matrix bulkhead junction itself, and my biggest issue is that I cannot seem to find one anywhere in the U.K.
Every one I see for sale online is from the USA, which obviously adds time and cost. Volvo dealers here in UK are mostly closed at present.

Does anyone have any ideas, or indeed where I could get one from, or is the USA possibly my only option?