I wrote a long response to the above but my browser decided to digest it. Apologies if I am blunt in my rewrite, the bluntness is directed at my machine, not you.
Change of journey is a refund, though. That's how it's accounted for in Lennon, just like disruption there's a separate refund code for it.
Accounting for things in Lennon in a certain way doesn't change the meaning of the English language. A refund fee is not a change fee and a change fee is not a refund fee, even if for the time being they are both set at the same amount.
Paragraph 5 of Part 1 of
Schedule 2 to the Consumer Rights Act 2015.
This says:
A term which has the object or effect of requiring that, where the consumer decides not to conclude or perform the contract, the consumer must pay the trader a disproportionately high sum in compensation or for services which have not been supplied [may be regarded as unfair].
(bolding mine)
This does not apply to change fees because of one of more of the following:
1) Changing a journey is not "not concluding or performing the contract", it is changing the contract. (Your argument might have more applicability to refund fees than to change fees.)
2) A term contrary to paragraph 5 "may" (not must) be regarded as unfair, so it is possible it also may not be. (Contrast with section 63 (6) which refers to terms that
must be regarded as unfair.)
3) Section 64 (1) (b) states that a term may not be assessed for fairness if the assessment is of the appropriateness of the price payable under the contract. In OFT v Abbey & Others [2009] UKSC 6 the Supreme Court ruled that ancillary costs were not eligible to be assessed as unfair for this reason. Although their ruling predates the CRA and was about the Unfair Terms in Consumer Contracts Regulations 1999, the wording of the relevant parts of the UTCCR and the CRA is almost identical and the ruling would therefore apply equally nowadays.
So no, that paragraph doesn't assist you – and if it did, I'm pretty sure the much higher change and cancellation fees assessed by airlines and hotels would have been struck down quite some time ago.