'm unhappy with their lack of transparency and unfairness

'm unhappy with their lack of transparency and unfairness. I had my device insured for R23 649 for close to 3 years with no claim, when it's time to claim they offered me a device worth R13 999. When I enquire, they say that it is a like for like insurance cover and do not cover the monetary value but the device itself. Yet no where in the contract does it say that. Why do they state the sum insured if that is not the value of will be compensated with should something happen