2020 TT Roadster Sat Nav update cost?

[BrianJS]

I think the maps on our sat nav need updating as it got confiused near Cambridge / Peterborough. I believe sat nav updates happen free of charge for 3 years and then??? I wrote an email to Audi UK to ask if and how our sat nav could be update and they replied:
I have spoken to a Service Advisor at Southend Audi, who advised that you would need to book your vehicle in to update your vehicle's satellite navigation. It may cost you 500GBP, the cost may vary depending on your vehicle model and what update is available. 

Really?!? I told them it was a 2020 TT Roadster. Map update £500?!? Has anyone had to update their sat nav? If so how and at what cost?