I have a similar situation, so I'll hijack this thread.
Bought a ticket via an agent, the reservation was changed without informing me, I noticed and applied for a refund. I got the refund which is ca. 20 GBP less that what I had paid initially. I asked the agent but they claimed some of the fees were non-refundable, without even mentioning what these fees are.
20 GBP is not a greal deal but I am not happy with this sort of making business. I paid for a service, did not get it, asked for my money back and did not even receive the full sum. Is this even legal? I paid with a debit card. Should I file a case with them?