the only thing your dad can do with that wall is to scrape it with a scraper.wet the wall with a sponge or spray with a hand sprayer let it soak in and where the paint becomes loose scrape off.when it's dry put some filler over the bits that came off,sand down smooth then paint.the water in the paint loosened some of the wall so wetting it again will show up any more problems.there isn't anything you can buy to cure this im afraid.it could be a more serious problem of damp getting in your wall from outside,get your dad to check or to get someone else to check if he's not sure.always cure the problem.
phil holmes
August 2009