Miscalculated Claim Excess fee

Someone should have informed me about them before I used their insurance. Phonehas been fully paid via contract, so has the insurance within the same time-frame . Just a mere screen crack that needed to be replaced, I was initially quoted R1875 excess. I asked them to give me a cost breakdown as to how they got to this amount. They mentioned I'm insured for R12 500 and I am to pay 15% of this. I explained that this did not make sense to me. Was told the same thing by 3 different people. Once I had, had enough- I advised I am with drawing my claim. Next thing I get an email stating they have miscalculated and I only need to pay R 877. The inconsistency actually brought me here to wake up and smell the coffee. What are the chances that my phone will be returned to me in the same state as handed in. Wish me luck