I'll cover some of the points and let others deal with your other requests.
1) The killer is unfortunately not reading the policy, and having someone verbally on the end of a phone line confirm something verbally when the original documents say something different is not going to help.
2) Sure, he can cancel his insurance, but that doesn't mean the monthly schedule of premiums just stop. He has purchased an annual premium paid for in monthly instalments. So the company has the right to charge him a cancellation cost and refund unused months, however it would be extremely rare if the refund due is in line with the monthly premiums. The detail will be in the terms of the policy, but a typical refund might be 50% of the premium after 3 months.
So he can't cancel without making further payments and they will take him to court for the outstanding amounts due at the date of cancellation.
Then there's going to be the issue of getting replacement cover - with a recent new claim to add to the record. As it stands he won't be reassessed for the additional claim until the normal renewal date for him in November 2015.
Probably better to maintain the current cover unless he is giving up taxi-driving completely.