BA/IB/Air Nostrum flights are refundable, even in Blue class, less EUR25 fee per booking. Vueling (and other carrier) flights are non refundable/changeable. This can only be done by call centre.

Call centre is pretty poor, as is the Twitter team.

Yes, IB has award availability on its flights where BA does not. It usually is in the Turista class. Sometimes internal connections with international will show availability where separate searches will not on IB. Eg., you might find OVD-MAD-SCL availability but not MAD-SCL.