Write to the insurers telling them that the basis of the contract of insurance has gone and they are no longer 'at risk' because the insured vehicle has been scrapped. Since the insurance was for that vehicle and the vehicle does not now exist the contract should be regarded as henceforth voided as impossible of performance by virtue of that 'novus actus interveniens' viz the scrapping of the vehicle.
Therefore the balance, as calculated from the date of scrapping, is no longer payable, and they should recalculate any claim they make accordingly and advise what, if anything, is due to them.
Worth a try.