10% Deduction on claims

Weeks ago my vehicle’s tyres got damaged by a pothole, I called the insurance to claim I was told they require 12800 for access fee. I opted for cash settlement instead which was a total of 3k on top of that the insurance said they are taking 10% from the amount because their service provider gives them discounts!! This is not in the contract and why does 10% have to do with your clients ?? I’m very disappointed