so you were originally booked a flight on 11 jan at 1550d - 0820+1a? now that flight is on the same dates timed at 1635d - 0900+1a?
ba mmb shows the new flight on 11 jan with the new timings, so ba mmb does reflect the change?
the call centre is right, a change of 40 minutes is not really going to give an entitlement to do a free change of dates