When my PP was at 3 years old I asked VW about the diff oil change. They did not have any knowledge of this.
They contacted VW head office and it tied up with other info online that there was a service scheduled.
This was around £60 and uses the regular Haldex fluid, from the colour of the fluid that came out I am glad I had this done.
For peace of mind and any potential future cost of replacement, I thought this was money well spent.
I have other cars with diff plates, the diff plates do not last forever, especially with old fluid.