Giles Corey is an interesting character--he is a bit rough around the edges, and tends to be cantankerous. In fact, he has gained a reputation in town for being one to constantly sue his neighbors and friends for various petty or even imagined offenses. In fact, in act one we learn that he even sued his good friend John Proctor for "publicly sayin' I burned the roof off your house." Proctor denies having ever said it, but paid up anyway.
In the end of act one, Corey goes to Reverend Hale with a concern that he has. He has recently married again, and he complains to Hale that his new wife is "readin' strange books" and that whenever she does, he finds that he "could not say [his] prayers" but as soon as she closes the book and leaves, he can say his prayers again. He is baffled by this occurrence, and wants Reverend Hale's opinion, to know if there is anything to be concerned about. He complains of this to Hale, who says he'll talk to him about it later on. That is the main complaint in act one. Before this, there is bickering between him and Putnam over land boundaries and firewood, and between him and Parris over sermon topics and salary. So, Corey is involved in many complaints in this act.
In act two he has good reason to complain as his wife is arrested for witchcraft--he goes to Proctor's house to talk to him about it. In act three he complains of his wife's arrest to the judges, and also about how Putnam is having his daughter accuse people that he can steal land from.
I'm not sure if that is what you were referring to or not--if not, feel free to submit a clarified question and I can help you with it. Good luck!