Zibuyile Tau, a resident of Alexandra Township in South Africa, holds a health insurance policy with a reputable insurer. The policy covers medical expenses for Zibuyile and her family. Recently, Zibuyile underwent a medical procedure and subsequently filed a claim with her insurer to seek reimbursement for covered expenses. She received medical treatment at a local hospital, which included surgery and post-operative care.  Zibuyile submitted a claim to her health insurer, detailing the medical expenses incurred during the treatment, including hospital fees, surgeon's fees, medication and other related costs. Along with the claim form, Zibuyile provided supporting documents, such as medical bills, receipts, prescriptions and the medical reports required by the insurer. Zibuyile alleged that a specific medical procedure had not been covered as promised under her health insurance policy. What is the insurer's primary responsibility in this situation?