I used an enzyme-based cleaner on a kitchen sink. It was draining before, now after using a plunger, it's completed clogged. I've removed the ptrap and stuck an auger in about 5 feet. When I use the plunger it brings up a sandy black sediment. Would another treatment of the cleaner help or make it worse?

My somewhat "quess" since you have to really be there to know what is happening is that you had some minor clogs up closer to the sink and dislogged them, which are now adding to the real problem of a major clog. You will find most plumbers have no like for most of the liquid and powder drain cleaners which often only make their jobs harder later. It appears the drain needs to be snaked further though the pipe to clean it out.