Quick update, after talking the mechanic out of changing the DPF for €1800, wasting money on a temp and differential pressure sensor I finally go to the botom of the issue - the hose going from the exhaust to the differential pressure sensor! I had asked the guy to check the hose (which of course he said he did) at the very begining of the ordeal. When I probed a bit further as to how he checked it before I shelled out on a DPF Unit, he had pressurised the open sensor end of the hose to check for blockage....never occurred to him there might be a leak! Anyways, when the hose was removed, sure enough, there it was, a pin hole!
Hose replaced now. Regen ran and blockage back down to 27%!