
I would use the biological washing powder too - apparently cold water works better than warm for the carpet fibers. I then steam over with a steam mop and a little bit of zoflora for a pleasant smell. I have heard people setting the iron on a cool temperature and steaming the area if they do not have a steam mop.
I would never use vanish shake on powder ever again as it left my boy with severe 'carpet burns' on his underside after one use and took weeks to heal. Can't say if my old hoover wasn't powerful enough to get everything up off the carpet after it had been worked in but the results were awful so won't risk it even with the more powerful Shark.