If a hollow plasterboard partition is damaged, cut a rectangular hole in the board slightly larger than the damaged area. Cut a piece of hardboard slightly larger again and make a small hole in the centre of it. Thread a length of cord through the hole and knot it at the back.
Apply liberal blobs of adhesive to the edges and corners of the hardboard's, rough surface, then feed it diagonally through the hole. Pull it into contact with the back of the plasterboard. Hold it in place until it is firmly stuck. When it is completely dry, cut off the cord and fill with repair plaster. When it has set, sand until smooth and repaint.
Screwfix is the UK's largest direct and online supplier of trade tools, accessories and hardware products. To view their range of plastering tools customers can visit the website here: http://www.screwfix.com/c/tools/plastering-tools/cat831284.
Bad advice!