People who use vernacular in Official situations and cut you out completely

I hate it. Simply hate it. Why do people do it? I recently shifted south of the Vindhyas and let me tell you it was great untill that started happening. People would simply start chattering in their adopted native language and I would end up feeling left out. That feeling where in you start feeling as if you've stepped on to foreign shores and are now left with nothing but a rudimentary understanding and you start to pray that you meet someone who might speak a language that you might understand.
English being a common medium goes for a toss as you being north Indian tend to speak in accent free tones while 'their' English is heavily dosed with their mother tongue. I challenge anyone to understand what 'they' say.
I never thought that I'd feel like a bloody foreigner in my own country.