It's interesting that you know exactly that it's clay from the description but they never really name it. That's a red flag for me. Also don't discount the fact that the people you're talking to really work for the company. Their response to how depleting clay is will be a tip-off.
If they tell you that is why the other ingredients are included, they're misleading you. If they really wanted to replenish what you lose through depletion, they would have it as a seperate supplement that you don't take within 6 hours of the clay.