Originally Posted by
mlafqtv
Travel agents can, if they wish, charge fees for cancelling/changing reservations - over and above any fees that may/or may not be charged by operators.
They should have made you aware of any of any applicable fees at time of booking.
Indeed, and if you want to change or cancel a BA ticket booked through Amex, you will have to pay both BA's fees (as defined in the fare rules) and Amex's own service fees which I believe are the aforementioned £20.
I don't think travel agents are able to avail of BA's 24-hour cooling off period - but they can do other things such as holding bookings without ticketing them immediately, and they may have an agreements with airlines to waive X number of airline change fees per month or similar.