2. それで話がおわったところではっきり断ったところ、「なぜ?たった今、興味を示したばかりじゃないですか」えらいことになってしまった。
My translation: "Then, when the pitch was over, when I firmly declined, [the salesman said] "Why? Just now you were interested, weren't you?" ... ??? ...
What does えらいことになってしまった refer to? I understand えらい means "great; excellent; admirable; remarkable, etc.", but I can't relate this to the context.