Replacement less than the insured value

i took Absa idirect Personal Insurance on my package i insured a cell phone to the value of R9000 paying R127.64 as stipulated on the policy document they have sent to me. i made a claim in past three weeks and what i don't understand the is a document sent to me that the claim is R3999.00 minus R500. when i asked how come am i am paying for R127.64 if the phone is R3999.00. i was also forced to accept a branded phone that is sold on line by the a certain distributor and no apology for that. What i know is each and every phone has has its premium depending on the value as stipulated on the policy document, when i asked how does this happens am told \the onus is upon yourself to make sure that you are correctly insured at all times\" . so the question is how do i make sure of that because i rely on the document that are sent to me to avoid being under insured if the phone depreciated why they don't send me communication that says this is the current value of the phone. which means i was paying more for less. in the communication in the previous communication they never said a word about the value to be replaced i only received an email that says i must sign and accept R3499.00"