Pre owned warranty

I took my car to RMI dealer and the dealer did an assessment and it was discovered that the oil pump has seezed which damaged the cam-belt and the turbo, however the authorisation letter from Innovation covers the engine only and it doesn’t mention that oil pump is faulty. However i to realise that you only include the Engine amount the Turbo amount and Cam-belt ( they both have separate cover amount) was not included could you please amend as revert asap as the vehicle is my source of income. While the oil pump cost more than R15K. And they only want to pay R8500.00. While the Turbo and Cam-belt has their own separate price