My shih tzu was very difficult to housebreak - he would look right at me as he did his business and wouldn't even stop if I said "Uh Uh!" He'd even keep peeing as I carried him outside. He finally figured it all out and was housebroken around 8 months old....
Belle came to live with us in Feb last year and we had sooo much snow and it was so cold that I decided to use pee pads. She got the hang of it with in a few weeks (not 7 days

) and once the weather improved we started outside training. She is dual trained, and actually prefers to go outside now - she even barks to ask to go out
Good luck with Prissy. One day it will all just click for her!