Agreed value isnt what you agree on, its what the company agrees to pay you out at the time of a claim Thats the correct term in the insurance industry.
Market values fluctuate all the time through out the 12 month contract.
Some insurers, on their policy wording will actually state, we will pay the agreed value or market value at the time of a claim, which ever is lessor. And some others will say we will pay out what the vehicle is worth at the time by their assessor, So even though your paying a premium on X amount sum insured, you maybe subject to a payout of Y amount.
My insurer isnt JCI either.