Jus to share my experience.
My first visit I went in asking things in English but the conversation was not flowing. My 2nd visit I spoke to them in Mandarin, they became "more friendly". Not saying that they were not helpful when I was speaking English but I think its just that thay are more comforatable speaking in Mandarin than English. Generally they are very helpful, straight to the point and reasonably priced.
Just my opinion.