Three tips.
One, if a dog has housetraining problems, don't leave them loose in the house! Put them on a leash, tie the leash around your waist or to a belt loop and have the dog follow you around as you go about your life. Go outside *with* the dog at regular intervals, praise quietly while they eliminate, then have a big happy party when they are done. For the happy party, let them off the leash, play a little and give treats. Then put the leash back on and go back to your life. If you are not at home, confine the dog to a crate or to a small room where they are unlikely to mark.
Two, I have a protocol that was tested with over 500 cats for successful re-training to a litterbox. PM me if you are interested because it's just too long to post here.
Three, the best cleanser I've found is Anti-Icky-Poo. It is not an enzyme cleaner, it is a solution of bacteria that literally eats whatever is causing the smell. I learned about this stuff from a woman who specialises in "incident" cleaning (cleaning up crime scenes). It works on blood, urine, feces, etc.