You need to jump through some hoops. Have your primary care doctor refer you for physical therapy and to specifically see the requirements for approval before they write the letter.
Insurance companies have different requirements for get per-authorization for surgery, such as documentation that you have tried physical therapy to alleviate your symptoms, special bras, analgesics, etc. Your surgeon should be able to help you with this, ask you surgeon to appeal your request, I have gotten several patients approved by appealing. Good luck!
I am sorry to hear about the difficulty you have experienced; unfortunately, it has been more challenging obtaining insurance authorization for breast reduction procedures. Persistence is often necessary.
Based on the literature you posted, the insurance company has provided your requesting plastic surgeon more information as to their reasons for "denial". Best to follow up with him/her for specific information and advice. Best wishes for authorization and an outcome that you will be pleased with long-term.