HI Alan,
first of all I sympathise - we have a 17 week old cocker boy who used to do exactly the same. If I put him in his crate at night, he's be up yipping madly and covered in poo 4 times out of 10, to begin with.
You sound like you are doing everything right, and to be honest it's just a long process. You need to be prepared for it to take a while - Indie is 17 weeks, and still has about 1 accident a day, though is managing to do the rest outside.
It takes a while till they get the idea, Indie really only got it at about 11 weeks, and things seemed to click a bit, as in some pee hitting the target. Make sure you have a clean set of everything, and I now give Indie his last feed at 6pm, so he does a poo before bed. When he does one before bed, we act as though he's just passed the crown jewels, and lavish attention on him.
I bought three sets of bedding, and now keep one in the car, one in his bed, and one clean - it saves time if there is an accident, though we don't have bedding ones any more. It's like having a newborn for the first wee while, but it does get better, just persevere.
Shona