That some brokers (I use the word in its broadest sense) apply extortionate fees and charges and / or are very cheap in year one but are sometimes much more expensive for the renewal, is hardly news. This section is full of threads on the topic. It comes second only to threads on ‘Who is best (ie cheapest on day one) to insure me steed?’. Yours is not the first and will probably not be the last.
Does the way Motor insurance is flogged in the UK need a shake up? Maybe, yes. Does anyone have the appetite to do it? Probably, no. Does it appear to fly in the face of treating its customers fairly? Sometimes, yes. Do the providers of the commoditised insurance in a mass market (millions of Motor insurance transactions take place a year) break the law or specific regulations blatantly? Probably, no. Do their customers bother to listen to the spiel they are told when they buy their mass market product from the chimps or some computer based search engine at the lowest price they can find? Definitely not. Would it make any difference if they did? Probably not.
Interestingly (or not) Devitt seek to explain the background to cancellation in their website, found by Googling just four words: devitt motorcycle insurance cancellation.
https://www.devittinsurance.com/motorbike-insurance/cancelling-your-motorbike-insurance/
What is maybe interesting (or not) about your case is that it appears from your opening statement:
1. That you cancelled your policy after six months had elapsed.
2. You were charged a cancellation fee of £55. Leave aside just for now whether this sum is reasonable or not, or whether it was detailed to you when you bought the insurance policy six months ago.
3. You did not receive a pro-rata return of the premium. The annual premium was, you tell us £250 (presumably paid in full at day one) so cancellation after six months at pro-rata would be £125. Logically, this would mean £125 less £55 ie. £70 back to you.
Yet you tell us that you received nothing at all. Did Devitt explain to you why the figure was zero? Did you ask them? If so, what precise explanation did Devitt give you? In short, why did you accept a zero figure when the basic sums (based on nothing more than the figures and details you have provided) indicate that you were due £70?