we are trying to shampoo our hall carpet, but someone had spilled quite a bit of laundry soap awhile ago and it doesn't seem to go away. Does anyone know a better way to get rid of this big blotch of soap on the carpet?
Try diluting some vinegar in water and shampooing with that. Vinegar is used to cut oven cleaner cleaning solution making clean up easier, maybe it will work on the soap. My concern is how much water are you putting on the carpet? Saturating it could be damaging the under layer, promoting mold. You might consider cutting out that section, taking it to the sink or tub and running water through it until completely soap free, plot as much as possible out, let air dry and then use double sided carpet tape to reinstall it in the hall. They use carpet tape when installing carpeting when it must be seamed, so it's not a freakish idea.