Why does so many costumer service companies have representatives who can't speak or understand English?

I have been on the line with some people from credit bureaus, cell phone providers, and other giant firms selling various products; the man/woman on the other line is not speaking clearly, i can't understand what he/she is saying, she/he can't understand what i am saying; their answers reflect their lack of understandment for the English language... why do companies hire costumer service reps who can't speak English!!??