Hey,
We have a 4 1/2 year old male british bulldog and they are such wonderful dogs, aren't they! ...
BUT it is typical of the breed for them to be stubborn and they realy just do their own thing.
With our boy, we get the best out of him by going with it- they are just babies in bulldog clothes! when he "screams" (we call it talking) just "talk" back.
They respond the best when you treat them as though you are on the same level as you (to a certain extent)
Hope that was some help to you.

Join one of the Bulldog Clubs - the details should be on the NZKC website www.nzkc.org.nz There will be experienced breeders in the club that will be able to help you.

Maybe, if you have time to take him to puppy pre-school,
worked wonders for our pup. Your local vet should have info on a puppy pre-school near you.