Although this comes too late for the OP, it may be worth a reminder. As explained in one of my recent threads, you may find that the discrepancy between the TA and BA was as a result of the currency in which BA quoted you the fare. If they quoted it in GBP it may have come up with a different fare (i.e. fare bucket, fare basis) than if they had quoted you in EUR. It is completely incomprehensible to me why this should be other than a POS issue, and I only discovered it very recently and after 15 years of flying ex EUR's ! Just a point to bear in mind.