On-going DPF / NOx issues P20EE -64 - Transit Custom 2019

Hello everyone, I am quite new to diagnosis and have a nightmare this year with a string of DPF issues on my 2019 Ford transit Tdci, basically the money has run out so im doing what I can myself so any advice would be hugely appreciated. In around May time my turbo blew on the motorway, I got towed to a dpf specialist who then charged me 4500 quid for a diagnosis and repair, of a new turbo, a new wet belt and a DPF clean. This worked fine for a whole 3 months, when I got a ‘drive to clean air filter’ message on the dash – the same as I got before so I took it to the specialist again and they diagnosed a dodgey DPF differential pressure sensor and broken throttlebody – They wanted 700 quid for the work which I couldn’t afford so I did it myself, changed the parts and reset the learned values & recalibrated the throttlebody with forscan. I then used some foam dpf cleaner and conducted a forced static regen – I then drove about 400 miles and monitored my DPF load, time since last regeneration etc etc – All seemed good, regenerations were occurring – although on this 400 miles the DPF regenerated I think 3 times which seems like a lot to me? But at least it was doing them, I plug in Forscan into the van after this 400 miles and a new DTC comes up P20EE -64, problems with the SCR Nox catalyst efficiency – having conducted the test on forscan this is reading as 11% (minimum 15%)

 Not totally sure where to begin with diagnosis – I am going to check the Adblue injector for crystallisation and clean it, although I couldn’t see any crystallisation around the nozzle.

I noticed a few things on forscan that I suspect are relevant: I swapped out the DPF pressure sensor however after resetting the learnt values the differential pressure now reads 0 regardless of engine on or revs, DPF_INP (inlet pressure) does vary and sits at 2/3 kPa at idle. This is with a brand-new sensor and the old sensor too, which makes me suspect that maybe the old sensor was not broken perhaps? It seems strange that with 0 differential pressure regens would continue to be happening – I am wondering if this if then preventing the right temperatures being reached in the catalyst.

Other values in forscan have seemed strange – Soot_load which previously was reading 120% before clean and regen now consistently reads 0 regardless of what the dpf load is, also long term ability for dpf regen sits at 0.02% - which seems awful low if regens are occurring seemingly without issue!  

I tried to remove the adblue tank so I could give it a clean however failed miserably – nor do I have a pump to empty the tank that way, I have bought some Anti-crystal additive and will top up with more fresh high quality adblue with the hope it will do something!

Any and all advice very appreciated!