The only thing I could think you could do is create a new policy and
cancel it within 14 days. There will be a cancellation fee and a pro-rata charge for the time you have been covered (worked out by the annual premium price).
Expect to pay £120+, but it's better than paying £434.
Not an ideal solution by any means, you might be better finding another option to needing the insurance.. if you need to make a claim or forget to cancel within the magical 14 days, it will be at least be expensive or open a whole can of worms