Vodacom Insurance Undisclosed Betterment Fee

What is this betterment fee that my sister or aunt have to pay to you when claiming for a new phone? Why was this not explained on taking up the insurance? Why is this not in the terms and conditions of the actual insurance document?

Why are you charging people fees they know nothing about when the claim terms clearly state that an excess fee of 15% needs to be paid plus the difference between the price of the two devices? What is this betterment fee now that needs to be paid and why?