The EEOC does not get involved in defamation cases unless there is also employment discrimination (e.g. racial, sex, national origin, age 40 or over, religion, or disability): the EEOC's mandate is to fight employment discrimination.The only way to get the recording would be to file a lawsuit, such as a defamation lawsuit--either against the specific persons whom you believe are defaming you, or you can file a lawsuit against "John Doe" or "Jane Doe," using fictitious names until you know the actual persons' names--and then, in the lawsuit, issue your coworker a subpoena for the recording. Only a subpoena can compel them to release the recording to you, and you can only issue subpoenas in a lawsuit.