Short term insurance dispute

I put a claim for a ****** cellphone huawei and nova 11 pro, and on the 4 December I received a call from Fnb Mpho informing that the claim has been approved. They compared prices and found that the cellphone was cheaper at takealot for R7999 and they will be sending me a voucher. I immediately rejected the offer as when I took the contract of the cellphone it's was R17000 and I requested them to insure it at R14000 so reduce the premium. I paid offthe cellphone contract last year already. The reason for reject was that when I took the cellphone insurance the agent whom I spoke with only explained about the excess of the cellphone which is R1500 nothing else. I checked the insurance document and nowhere does it states that should there be an unforseen circumstance where the phone is ****** fnb will only pay half of the amount of the cellphone. The website where they want to give me the voucher, third parties are selling on the website and I cannot guarantee the authenticity and legitimacy of the device therefore I will not accept the offer. I'm very disappointed with Fnb and I want them to sort out this matter as soon as possible. Mpho did not seem bothered when I told her I'm will be taking further steps regarding this matter it just shows the lack of customer service I had to endure. I have been a client of Fbn for 19 years and I must say I'm very disappointed. Fnb should do better than this and give me what's due to me. I have never missed a premium I deserve good service.