Firstly I suggest you change your dealer, they do most definitely update maps and the nav system if they are an official Kia dealer. But it costs £30 now.
Have you checked if there is a map update for your system? Long press on the Right hand knob will show your current "Device information" Mine is as below:
Software ver. : YN.EU.SOP.10.2011
Firmware ver. :YN.EU.SOP.10.140
Navi app ver. :YN.EU.SOP.13.51.58
Map ver. :EUR.1.49.49.001.001(D.H1)
Your new files will need to have the same prefixes with higher version numbers.
Somewhere there is a table of updates!!
The flap/slot is immediately under the up and down arrow buttons for tuning and says SD MAP on it
There are many threads on this site about updated.
I do not think that in the UK you can simply update the map from a file. (The Kia UK updated agreement was outside the general Europe update agreement.)
But I would be happy to be proven wrong here!
Also this slot is used to update the car system firmware.
Thirdly the map updates are way behind. In particular, changed speed limits are at least 5 years behind in my area and there have been a lot of places reduced from 50 to 30 or the boundary has been extended for the 30 limit. (We also have "30 Zones" now in the middle of higher limit roads!) Mine was updated in January 22.
Best of luck
