Why S Voice is not functioning as earlier/ after the new update?

[AC Question]

Hi I am using Samsung S6 from last December; it was pretty good and very user friendly but unfortunately after the latest software updates (Marshmallow) the S voice does not supporting and recognizing the caller information. It is really embarrassing me and I tried to contact Samsung official support site but since my phone is manufactured in Vietnam they are asking me to contact them, unfortunately the Vietnam site is not in English. Why Samsung is only helping to UK and USA???
Samsung is only providing solution for their UK and USA customers, if so then they will have to sell only to them…Vietnam factory also own by Samsung right???
Please someone can help me if possible