As this thread demonstrates, without details from OP, there is not much to be done.
1. Is this a refund of the air ticket he chose not to use. That is one of his options under the Regulation.
2. Is this a reimbursement for DOC expenses (not a refund)?
In the case of an unflown ticket, the former is easy as there is nothing to calculate or review. The latter may be a bit more complex and people who have used self-help do not necessarily have their expenses reimbursed without someone taking a bit of a look.