Is it permissible to report a factory that intends to cheat after it canceled the agency agreement and caused injustice and harm? And is it permissible to supplicate against the oppressor?

The agency is a permissible contract, but if its termination leads to harm, then it is not permissible to terminate it. So, if it is established that the factory has wronged your friend, they must ensure not to harm him, such as by taking back the goods from him or enabling him to sell what he has before revoking the agency. He is permitted to supplicate against them to the extent of the injustice. If the factory's deception is proven, he should advise them. If they do not respond, he is obliged to inform the competent authorities if there is no harm to him in doing so, as this falls under enjoining good and advising.