My father was covered in a group insurance policy through his employer. he was diagnosed with prostate cancer. He was approved for the operation.

I am sorry to hear about these issues you are having with your father's insurance company.  To begin with, there should not be a problem with the insurance company talking to your father about this.  Your father is covered under the group policy and they should not require to talk to the employer.  I recommend writing a letter to the insurance company outlining the entire scenario and explaining why you think the operation should be covered, etc.  Write in the letter that you are "appealing their denial of coverage" for the operation.  Explain everything as much as possible and include any bills and other written communications you may have had with the insurance company. I would also go ahead and request a copy of the insurance policy if you do not already have one. It is best to do as much in writing as possible so you can  have a clear record of all communications.  You can seek the advice of an attorney if you like but I would go ahead and try this appeal letter first and see what happens.  Maybe you can at least get the attention of someone who can help you further.  If you do not hear from them after 30 days of writing the letter I would seek the assistance of a local attorney if you still desire assistance with this.  Don't wait too long on doing anything because their may be some time limitations.  I hope this information helps you and your father.  Best of luck! NOTE:  This response is general in nature and should not be considered legal advice.  No attorney-client relationship exists or is formed by this information.