That type of stained concrete has a light coating of stain on the surface and if you hit it with a Monkey Pad or any other abrasive pad you will scratch the stain off. You can put a coating on it. The customer asked for 'wax' which is how they view it, but water based 'wax' for concrete is called 'guard' and it has chemical bonding agents in it to make it stick to the concrete. You can get Ameripolish 3D Stain Guard or Sentinal Formula 404 from your local Aramsco Interlink Supply. Give it a light scrub with neutral cleaner and organic citrus, rinse well, apply 1 or 2 coats of guard, collect your money.