I highly recommend Neil at Barracuda in the Shire - he has done an awesome job on a range of repairs - NP wave and race sails.
Neil and his crew are awesome, have great knowledge of windsurfing sails and very reasonable prices too. Located in Caringbah, worth a bit of driving
From memory I think Barracuda are having a break until 12th Jan? It's on their Facebook page...
Edit: Sorry, closed 'till 19th Jan