For IB issued tickets, on IB codeshare (BA operated) flights - is there any sense of how major the schedule change would need to be in order to trigger a full refund? Or are even minor-changes eligible? And how does this work if the outbound has already been flown, and the schedule changes are to the return journey?

In my particular case, an open-jaw ticket was issued in Brazil, via Iberia's Brazilian website. Outbound (Brazil -> Europe, operated/marketed by BA) is flown. Return (Europe -> Africa, IB codeshares on BA), are confirmed for future dates, and have recently been subject to a schedule change (10 minute earlier departure).

Ever since the schedule change, I've been unable to access "Manage My Booking" until and unless I click a button that I "accept" the changes. I have not yet done this. The only other option is to "refuse" the changes, which when clicked upon kicks me out to a page inviting me to call Iberia reservations.

Truth be told, I'd be very glad to get a refund of the unused flights - but before I call and insist, I want to have some sense of what my rights are (either by IB policy, or by Brazilain consumer protection law).

Or in the worst of cases - if I anyway abandon the tickets and cancel before departure, how can most cost-effectively request refund of the gov't taxes/fees in connection with the unused flights?