After a long, patient and polite explanation of the rules the changes were made the first time (approx. 90 minutes on the phone, about half the time on hold). Then they purported to take payment (the fees were pending on my credit card but then disappeared). Presumably through lack of payment the flights were marked as cancelled. A couple of days later another hour or so on the phone got the flights reinstated on the reservation but two days later they have not been ticketed and there is no record of the charges being debited from my credit card. I fear another 60 minutes or so on the phone is in prospect.

I accept the error in having engaged with this lot in the first place...but this simply should not be so difficult.