There has not been a shelter dog I have ever adopted that has not had to be rehousebroken. The problem is that even a week in the shelter undoes all the housebreaking that they have learned because they are usually required to "go" in their living quarters.

Just remember to give great praise when they "go" where you want them to - they will learn very quickly that your house is not one big pen.

Oh yeah - invest in at least a gallon of Simple Solution. Keep working on it - this too shall pass.