What should I do about false oral allegations at work?

I am a government servant. My superior (controlling officer) has made an oral complaint against me to the administrative wing of the Department. All the allegations are false and irrelevant, and I have digital evidence to prove my innocence. The Department has forwarded a note to the concerned section, mentioning the oral allegations, and is asking for a written explanation. However, no formal communication has been made to me yet. In these circumstances, what legal action should I take? The allegations have seriously affected my dignity and reputation in the office.