Globaliser

Using today's prices, that figure for taxes, fees and charges looks about right for WT+ outbound.

One thing to try to get the listing of the outbound flight in your BAEC account is to go to this page - https://www.britishairways.com/trave..._gb?eId=172705 - and either search for 20 transactions of flights only, or specify a date range that covers the date of your outbound travel.

When you say you can see evidence of the outbound journey in your Avios and TPs, are you sure that they weren't reduced when the flight in question was removed from the BAEC welcome page?

Going back to the fare, though: for your travel dates, the lowest published W class fare if purchased during the February-mid April 2017 period looks (on dip samples) to have been stable at £2,986 (plus TFC). However, you only paid £2,108. One possibility is that Expedia sold you a negotiated fare in the outbound direction and a published fare in the inbound direction. The latter would have been £1,493. And that would imply that the outbound half was fared at £615 - the figure that BA quoted you.

However, it would seem odd to me (as a non-expert) if the Expedia fare was calculated like that. It's more likely to have simply been a negotiated fare of £2,108 round-trip (ie £1,054 attributable to each direction). Starting from that hypothesis, the £615 figure that BA used may simply have been arrived at by someone reverse-engineering your base fare from the published figure, as above ("he paid £2,108, and the inbound fare must have been £2,986 x 50%, so the outbound fare must have been £615"). And that possibility would make me keep on pushing, if I were in your shoes.

And, as others have said, you must be entitled to have the excess APD back as well.