A4 2004 1.9tdi sport 130 ECU

I'm new to this forum and am looking for advice. Bit of a story first. We have a A4 1.9tdi sport 130 2004 auto and looks like the ECU is knackered. Car was fine then on warm day after 30 mins motorway driving stopped at lights and the power completely went when pulling away but engine still running. First 3 beeps and solid amber ABS warning light followed by big red brake light warning then EML have attached photo of dash. Car would not move at all but engine running. Fault code P0600 serial communication link fault. Went back to tow car 5 hours later and it drove fine but EML on. Same happened the following day. Sent both ECU and ABS Module for testing and found no fault. Any ideas. I know ECU in this model is a common fault and thinking about replacing it with used part. If so will I need to recode the new ECU and does anyone know who does this. Or if I also get immobiliser module, keys, ignition, locks is this a plug and play? Any help?