MiWay not honouring a valid claim

I lend my car in good faith to a person with a valid drivers licence. I confirmed that he was not under the influence nor that the speed limit would be exceeded. MiWay refused to honour the claim as the driver exceeded the speed limit at the time of the accident and then stated that I did not “TAKE REASONABLE STEPS TO PREVENT LOSS”. How do you take reasonable steps to ensure that the incident driver does not exceed the speed limit when you are not in the vehicle? Shocking. I am now paying for a car that is written off and am unable to fulfil my job as a sales person.