Try here Ken , i have heard good reports about them mate - http://www.camperinterior.co.uk/html/vw_camper_van_roofs.html
Just be aware that the fitted size is not the supplied size. Whilst it is possible to fit a used canvas with difficulty, they are normaly supplied with extra material to allow for pulling in at the corners etc. Why not have a word with Dormobile themselves. Its not the original company but I do believe they market replacement roof bellows for VWs.
