To what extent does this sloppy work matter?
If the work will never be visible, and is structurally OK (level, straight, correct mortar mix) it doesn't matter. But don't let the sloppiness go unremarked. Because its part of the 'way' which your builder operates. And pay him.
If it does matter - isn't level, perps all over the place, wrong mortar mix, is off line - then get it put right before any further work is done. And don't pay until it is right.
People and systems show themselves for what they really are when things go wrong. Handled very carefully this issue could really help your build a lot.