Onobond - I can see if I'd noticed within 24 hours I'd have had a much better chance of sorting it out. I did ask nicely, and have a track record of correct bookings, but the rest of the points wouldn't have been relevant to my case. Glad you got yours sorted out though

Globaliser - I don't wish to travel next Wednesday. I'm not flying out to Sweden until the beginning of April, so there's no way I can take a flight from Sweden to England next week.

When I initially called customer services, they told me the cost of changing the date of flight would be around £90, which was more than I'd paid for the flight in the first place. I've just looked at cancelling online (didn't realise that was an option, thanks for pointing that out) - I'm entitled to 8SEK (about 80p!) refund - I don't think I'll bother. I can just hope that another error is made and they accidentally credit me with the air miles anyway

Thanks for your input everyone - lesson learned for next time, don't be too trusting, and check everything from BA very closely immediately after booking.