Just posting this in the hope of saving someone a bit of wasted effort.
The 2010 and 2011 model sat nav updates are via dealerships only
The latest version they produce is 2014/2015
They will not be producing any more updates
Dont bother..use your phone. Gone but not forgotten, 2005 RRS SC first edition, BMW 2010 Z4,TVR Tamora, TVR Cerb, MERC SL 55 AMG, E46 M3, Z4, Jag S type R, Skyline R33 GTR 640 bhp, Evo FQ 400, L322 RR, X5, Lotus Esprit V8 twin turbo, Lotus Elise 135r, Nissan Murano, Honda S2000, 911, Boxster s...and a few more

+1 for that advice.

In fact, back when it was still 2013 I tried to get an update and the dealer gave up, it was so hard. I used my phone (iphone 8Plus then XS Max) with this rather nifty holder:
https://www.amazon.co.uk/dp/B07FC6W1CK L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso
RRS TDV6 HSE Lux (MY2011)... Nara Bronze / Arabica - now gone!