If this was purchased as a single ticket, with luggage checked through you are entitled to a refund. Are you based in the UK or the US? If in the US start by writing to the DOT, and notifying US Airways by certified letter thay have 30 days to respond to your claim or you will file in Small Claims Court. If in the UK, file a complaint with
Send your complaint to:
Passenger complaints
Civil Aviation Authority
CAA House
45-59 Kingsway
London
WC2B 6TE
Or call
020 7240 6061
http://ec.europa.eu/transport/passen.../en/index.html