In hindsight, I wish I'd just changed the faulty injector with a brand new one instead of a remanufactured one but they are so expensive. I think a lot of people get their injectors/EGR valve changed by VW warranty after having the software fix applied and then reverse the software to pre-fix level (earlier than 9976). There is a Facebook group 'EA189 Fix Reversal Assistance (VW Diesel Emission Scandal)' that can help find a place to reverse the software fix if CT Cars can't (or won't).

three hours at another VW 'specialist' who thought they could do it but couldn't. Other VW specialists said they could 'try' but couldn't guarantee they could apply the software.

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I did also buy another brand new VDO A2C9626040080 injector to use as a spare in case the remaining 2010 original failed, but that that is still in its sealed box in case I ever need it. I knew about the warranty for the EA189 fix but was out of the 2 year warranty period. Stupidly I didn't think to get additional warranty for the engine. I read somewhere that the injectors could not be mixed. Can anyone confirm whether I can have three old 03L130277B injectors and one new 03L130277S injector together or whether I need to ensure that all four are 03L130277S?

Yes, I have a copy of VCDS and programmed the 6 character IMA code from the top of each injector(s) into the ECU. Did you or your mechanic do this? This is important. You can buy used but there is always a risk that the replacement injector has the same problem in the future and no or limited warranty (there are probably lots of people selling used injectors that may have been replaced so you need to be careful). Also injectors do wear and therefore I think you are more likely to need to run the minimum deviation adaptation than with new injectors - interesting link here from someone who bought used. The garage did program in the injector code but didn't do the injector deviation, I don't think they had VCDS.

In trying to 'chase' the injector deviations to as low as possible to zero (which probably wasn't needed) I ended up changing three injectors: https://www.darksidedevelopments.co.uk/products/1-6-cr-tdi-injector-removal-tool-for-cayx-engines.html I phoned my local VW dealer who told me that I needed part number 03L130277B (same as fitted to the car), however, two other VW dealers told me that I need 03L130277S (updated part). From my research the Siemens VDO injectors in the 1.6 TDI common rail engine are prone to failure (e.g. highlighted here) and VW have released the updated part 03L130277S (e.g. new VDO part#A2C9626040080 versus old part#A2C59513554). I also see Crasher mentioned here that he only fits the later VDO part. One difficulty I had was finding a local independent VW garage who had access to and knew how to use ODIS Engineering. I'd previously wasted VW Caddy III Kasten, Kombi, (2KA, 2KH, 2CA, 2CH,2KB, 2KJ, 2CB, 2CJ ) 1.6 TDI with 75 KW / 105 HP / 2010.08 – 2015.05

VW Caddy III Kasten, Kombi, (2KA, 2KH, 2CA, 2CH,2KB, 2KJ, 2CB, 2CJ ) 1.6 TDI with 55 KW / 75 HP / 2010.08 – 2015.05 Siemens common-rail injector, for vehicle Audi A3, Seat Leon, Altea and Ibiza, Skoda Octavia, VW Golf, Passat, Polo and Jetta, with 1.6 TDI diesel engine, with 90 and 105 HP, manufactured after 2009. I also ran the minimum injector deviation program (performed separately to the IMA code programming) via VCDS. I never bought a 03L130277S injector from VW. But I seem to remember it was the application of ECU software 9971 and running of minimum injector deviation which stopped the car from idling so badly (fluctuating up and down).