I would advise sending the phone into a Sony authorized service centre as the repairers will be able to test that the water resistant nature of the phone is maintained after repairing the port cover. Please note that operating on the phone yourself may void the warranty.
Well if you're keen on fixing it yourself, you can order spare parts from third party parts resellers online, including the flaps. There is a video on YouTube that shows how to replace the flaps and it looks very easy and straight forward.
I would advise sending the phone into a Sony authorized service centre as the repairers will be able to test that the water resistant nature of the phone is maintained after repairing the port cover. Please note that operating on the phone yourself may void the warranty.
