There are multiple products on the market like Nature's Miracle or Simple Solution. You can find these products in most pet stores or online sites. I like jbpet.com
You will probably need to apply several times to effectively neutralize the areas. There is also a black light you can use to locate areas you may not even be aware are there. Also in the cataloge.
You may want to try covering the areas with furniture or aluminum foil. Do NOT leave them unattended with the foil. You can try to be creative and use some other objectionable object to deter them from using "the spot".
Most importantly, the dogs need to be re-trained to meet YOUR standards. This is not easy and many factors determine how difficult it will be and how successful. There is a trainer who I love and have used, Bashkim Dibra. He has several books and is very well respected. He uses the crate training method. Really is the only way you will probably be able to address this. You should also contact your vet and have the dogs checked to ensure there is not an underlying problem. They should also be able to help you with behavioral techniques.