Yeah.
I usually end up tackling any local matrix repairs. Basically remove dashboard, disassemble heater system, remove heater box, replace matrix and rebuild.
EP91 is handier than EP82 thanks to the design of the matrix connections.
As a quick fix you bypass the matrix to remove it from the heater system. Find the inlet and outlet pipes that carry coolant from the engine bay to the heater matrix. This is them at the back of your engine bay:
And loop them together securely. It'll mean no hot coolant will circulate through the heating system in the cabin but the engine will function normally and be safe to use. This will keep you mobile.
It's important to do this incase the matrix suddenly dumps several litres of boiling fluid into the front footwells...
Now, just to give you a heads up, the next picture is only to show you what the heaterbox is and it's position behind the dash. Do not shit yourself as the interior doesn't need to be stripped to this extent!
You are aiming for the centre box in the middle of the bulkhead:
Closer look:
Even closer:
It's a case of removing the matrix from the heaterbox and fitting a new one. You can normally do this by dropping the dashboard forward and cursing at the heater system heavily. Here is the carnage of an EP91 replacement:
After removing the heaterbox, split it and replace the leaking unit.
Hope that offers a heads up and doesn't scare you too much mate. It's just a case of being calm, methodical and remembering where all the bolts go.
Jay