TFG Insurance is a ****!

My sister insured her phone in 2021 with TFG - the ********. She lost her phone and send her claim through which was approved. The amount approved is R3100.00. I went with her to take a replacement phone. The phone she wanted cost R3499.00 and we were told that we can't as its over the approved amount. We indicated to the sales lady that was assisting us that we will pay the difference and we were told that it's not allowed. The store (Mall of Africa) did not have phones for R3100.00. Phones were 3499 upwards or at a very low rate of R2499.00 or R1000.00. Can those that know the consumer law better, please assist as I don't believe that she should be forced into taking something that she does not want or something or a lesser value than what she deserves.