I have just had this job done on my 2016 VRS EA888 Gen 3, 50k miles. I had been topping up coolant for well over a year, putting off the expense of the job. In the end, it was getting through half a litre a week and so time to get it done. I also had an engine warning light P2681 - Engine Coolant Bypass Valve Control circuit open. Each time I reset this, it would be back on within 30 mins of driving and so was unlikely to get through its next MOT.
I got my usual non-specialist, independent garage to do this job (as others have said, I have done a bit of DIY work on cars but this job is a not a simple one).
I was quoted £660 fitted including VAT which is less than I was expecting (South Birmingham area). They did the job without hassle and the issue is fixed. I am not sure if an original or pattern part was fitted - it was Schaeffler branded.
I asked for the old part back so I could autopsy. There is a circuit board controlling a motorized valve, this board is not potted and so should be dry - it wasn't and had obvious corrosion. This appears to have been the cause of the P2681 error. The water pump impeller was plastic and there was evidence of cracks forming around the shaft and so that's another potential issue sorted.
If anyone would like details of the garage I used for this job, please feel free to send a PM.
Rich