Hiya m8. I've got the exact same software version as you and I ALSO have these really annoying bluetooth problems with my iphone. Cannot play music for 1 min without it randomly disconnecting. I'm considering updating to that version.
U can find the software RMC_EU_K16158 here:
https://www.audiworld.com/forums/audi-a1-191/audi-rmc-mmi-firmware-software-update-not-maps-2978650/