Paving not even and firm - what helps?

Gravel is underneath - so I called it gravel, that is the gravel. The sand is only used to fill gaps and to even out irregularities. I didn't find that wrong.

You can also lay paving stones on sand, but gravel is usually better because the sand can be washed away. Normally, you spread crushed stone (which you have) and compact it thoroughly with a plate compactor. On top of that, you spread about 5cm of gravel and screed it with a screed board over the embedded steel pipes, creating an even surface. Then you lay the paving stones; for natural stones, you tap each stone into the gravel bed with a rubber mallet so that everything is level. Finally, everything is jointed with jointing material and carefully compacted.

Best regards
Sabine

The clever bee is right!

Mmh, that doesn't help me at all. The guys did it all like this. Below is gravel, which is very firm, then they used more gravel for leveling and then a bit of sand so that the stone lies flat. Then they hammered every single stone firmly with the hammer. Afterwards, sand was put into the joints. It also looked great until the small vibrating plate came. After that, it was crooked and uneven.

I'm also not concerned about how to do it correctly. The question was, can I fix it straight again with a decent vibrating plate?

Remove stones, place gravel underneath with the rubber hammer on top, and then tamp down

You get the whole thing firm when there is enough split underneath (new, not the old compacted one). Not right now. Sand is not compactable. You can carefully set the stones in sand, then the slab goes on and everything slips.

For compaction
Water the driveway beforehand.
Walk very slowly, almost falling asleep while doing it
Bigger plate - different frequency - different compaction
Definitely use a rubber mat under the sole, don’t let the stones get damaged.

For a level surface
Take out and redo as described above.