The Sebo will not be much good on this type of job and the same goes for the prespray gold. Get yourself a cheap standard speed rotary machine with carpet brush for agitation, you can also use this for bonneting. There are a multitude of detergents to use, Chemspec enzall, Prochem powerburst, Hydramaster fastbreak etc, to name but a few. Make sure you use an acid rinse. If you are feeling energetic get a carpet brush, this will do a better job than the Duo.