Dog is not potty-trained when I was told that he was, what to do?

I'm currently sitting a dog and while he's a sweetheart, he has already done #1 three times all over my floor and furniture and done #2 twice. This is only day two. I have been walking him but he just does not seem potty-trained. The owner told me he was and said he would use pee-pads; I don't know if she was being honest or not. He has been ignoring the pee-pads completely...

Is there anything I can do at this point? This is a 5-day stay and I am rather frustrated about cleaning up after him. I do not wish to do this for another 4 days.