Claim insurance device

Hi I have a problem with cell c device claim insurance, they take forever to respond their emails telephonically their staff members are very disrespectful. I lost my phone last week I did notify them immediately and process the claim. This is what was explained to me regarding a device insurance max.cover R20 000 that is what I pay R 252.17 monthly insurance claiming for Loss or Theft, your excess is 20% of your device value R1250. They are telling to pay an excess fee of R3099.80 when i ask why so much they said kindly note that your device insured value is R15499, the fore 20% of the value of your device multip**** by 20, divide by 100 is R3, 099.80 this information I was never told only now since am claiming what happened to fair and responsible marketing, honest dealing. Please assist