New bathroom walls double-tiled

Hello dear experts,
Despite searching, I could not find anything comparable.
The following problem:
We recently bought a new condominium.
In the course of the bathroom work, the tiler installed the wrong tiles on the wall.
After we complained, the construction manager assured us that the wrong tiles would be removed, the underlying drywall replaced, and the correct tiles installed.
Now I have noticed that the tiler simply tiled over the wrong ones.
What now?
Thank you very much for your help

Now I noticed that the tiler simply tiled over the wrong ones.

Your "damage" is a bathroom about 1cm narrower and shorter. Where exactly does that bother you?

we were assured by the site manager that the wrong tiles would be removed and the underlying drywall replaced

He fooled you: you can’t just knock off drywall like that, the drywall would then have to be redone (at the tiler's expense, but not by him).

Construction is mostly rough motor skills, you can’t just click something away ;-)

The damage is not just the smaller bathroom. If renovation is to be done, everything must definitely be removed. Also, no one knows if the tiler used a special adhesive. According to DIN, this also would not be a proper execution in a new building. And last but not least, it is fraud, because we were assured that the fault would be corrected.

Tile on tile is not exactly the proper way to do it. But the defect has "actually" been remedied. In construction, much also has to do with proportionality.

During a renovation, everything must be removed in any case, whether it is 1x or 2x tile.

I can understand your frustration, but you got a bathroom with the right tiles. One can also assume that the tiler used the correct adhesive.

DIN are only guidelines and not mandatory. You should check your contract again regarding this.

Quote:
The application of standards is basically voluntary. Standards are not binding; this distinguishes them from laws.

Source: DIN website

So in your case, I would try to negotiate a longer warranty period (tiles could fall off in x years) and at the same time a discount, since the bathroom does not quite correspond to what was ordered. But don't immediately resort to legal threats; that leads nowhere.

For a 7.5 m2 bathroom, what would be an appropriate discount? If we insisted on making it new, sanitary fixtures would have to be removed, tiles and drywall taken down, drywall (2nd layer) renewed, new tiles laid, sanitary installations redone. To be done

For a 7.5 m2 bathroom, what would be a reasonable discount?
If we were to do it as new,
Sanitary fixtures would have to be removed,
Tiles and drywall taken down,
Drywall (2nd layer) renewed,
New tiling,
Sanitary installation redone.

To be done

Did you negotiate that verbally or in writing? If verbally then......