Loss of Voice Control after updating maps

I am looking for the right "ASR / srd" files for British English to go with City Navigator Europe NT(Unicode) 2014.30. I can see from the forum that other people are in the same situation. If it is true that you need the right ASR or SRX files to go with each new map, why are they never included? Are there different variations of ASR or SRX files for each model of Garmin Nuvi ?? If not, why not upload the files ?

I have updated the map file, the 3D images and the junction views (JCV) but I keep getting errors when I try to use voice activation e.g. when requesting "Find address" my 3790t replies "This feature is not available for Belgium" and when requesting "Find by name" my 3790t replies "This feature is not available for British English".

Here's hoping for a (helpful ) reply ;-)

The problem for nuvi 3790 is following: is came originally with City Navigator NT (not Unicode!) and there are not so much devices of this type sold with lifetime update. Now all current models use City Navigator NTU (Unicode) and most of them have lifetime update included. So additional files mostly available for current nuvi 2xxx and 3xxx models but not for 3790. ASR/SRX from 34xx and 35xx models are not usable for 3790.