Originally Posted by
Globaliser
As others have said, you can cancel but almost everything you've paid will be non-refundable.
In any case, what is the "exorbitant" change fee, and why? The current BA O class fare for CMN-LHR-CMN (which has a base fare of £16) is changeable for a change fee of €50 plus fare difference. So if you're being quoted a big amount, the chances are that it's because the CMN-LHR flight(s) you want don't have anything left in the lower booking classes, and the bulk of that amount is the fare difference. If you book a new ticket now, you'll still have to pay that high fare, so it sound like you're unlikely to do better than simply changing the ticket.
The absence of any details in your rather abstract question makes it impossible for any of this to be researched and tested, though.
Why is almost all of it non refundable? When the base fare is so low, surely that means most of it IS refundable in terms of taxes etc?
In the case of my LHR-MAD-LHR flights which were often £9 base fare, rest taxes and fuel, it was almost always cheaper to just cancel it and take the taxes back, even minus the fee, than to pay the £60 admin fee to amend. I was also better off booking returns for £100ish, then cancelling the inbound and getting £30ish back and effectively just paying £70 for a one way, rather than the £300+ ish figure the one way fare was priced at.
I didn't do it deliberately, but I did do it often, as was my right under the fare rules, due to many last minute changes to plans.