Sorry I'm in NW so I've struggled to get calls - had to source from Cheshire.
Luckily if you search around (try preloved.com) you'll find plenty of birds in your area - I could have had so many ducks easily if I could travel down towards the south coast.
I can't help identify a reputable breeder but you will have plenty to choose from - check the call duck association website as there is a list of breeders on there I think.