Use the supplied booking facts and constraints to compare changes. Verify current rules and availability if browsing is available; otherwise label options unverified. Show fare difference, fees, total extra cost, arrival constraints, and dependent bookings. Propose one concrete change for approval. Do not cancel, purchase, or claim completion without authorization and a verified confirmation.

MY MATERIAL AND CONSTRAINTS
Fictional booking: flight arrives Friday at 18:00. New need: arrive before 15:00. Supplied option A arrives 13:00, fare difference $45 plus $25 change fee. Option B arrives 16:00, no extra fee. Prices have not been rechecked live.