Repair of my Sony NV-U53G Sat Nav?

I have a Sony NV-U53G sat nav. A week ago on switching it on the GPS status symbol remained RED and I could not pick up any GPS signal. When I try to enter a destination I get a message ''GPS reception is currently not sufficient. Navigation starts automatically as soon as GPS reception is OK again.'' But it didn't and hasn't since that day. 1) Can it be repaired? 2) If so where can it be repaired? 3) How much will it cost?