Be aware that Devitt as a broker can and will charge "industry standard" cancellation fees. In my case the Ombudsman has advised that it is acceptable for them to charge £50 to cancel a £73 policy into which I had already paid £53. The total charge currently being demanded is £79 ...more than the cost of the original policy.
Legally they can do this it seems, so perhaps it would be wiser to go direct to your insurer of choice and cut out the middle man