Can you call to cooperate with the investigation if you can't go through the investigation?

No, it is the duty of every citizen to assist in the investigation. This is stipulated by law. The Criminal Procedure Law, the Public Security Administration Punishment Law and related procedural provisions are all mentioned, but they are not mandatory, which means you don't have to explain the reasons.

Criminal Procedure Law of the People's Republic of China

Article 43 With the consent of witnesses or other relevant units and individuals, defense lawyers may collect materials related to this case from them, or apply to the people's procuratorate or the people's court to collect and obtain evidence, or apply to the people's court to notify witnesses to testify in court. With the permission of the people's procuratorate or the people's court, and with the consent of the victim or his close relatives or witnesses provided by the victim, the defense lawyer may collect materials related to the case from them.

Article 44 A defender or other person shall not help a criminal suspect or defendant to conceal, destroy, forge evidence or collude in confession, and shall not threaten or induce witnesses to commit perjury or engage in other acts that hinder judicial proceedings. Anyone who violates the provisions of the preceding paragraph shall be investigated for legal responsibility according to law. If a defender is suspected of committing a crime, it shall be handled by an investigation organ other than the investigation organ where the defender undertakes the case. If the defender is a lawyer, he shall promptly notify the law firm where he belongs or the lawyers association to which he belongs.