Here you can see very clearly again that different stone colors and patterns can cause enormous problems. It is incredibly complicated to lay when you have to inspect each individual stone to see whether it fits or not. A landscaper can hardly manage that, unless you explicitly book that service. Because then he has to charge significantly more per square meter, as the job also takes considerably longer. You can always immediately tell who did their own paving. The professional does it well and neatly, but only you can do it perfectly. Because the last 5% towards perfection costs 50% more time.
On the current topic:
The manufacturer/your dealer is offering you a 50% discount on their stones. What amount is that actually? It’s hard to estimate how high the price per square meter for your paving stones is. Does such an amount come out where it’s worth maybe overlooking something?
At most, you could accuse the landscaper that he should have seen the wrong pattern earlier and stopped the work or mixed it differently. Maybe you can get him to swap a few stones cost-neutrally (roughly half a day) to fix the worst spots.
In the end, you console yourself with the 50% discount and let it go. The stones will also fade heavily, as can be clearly seen from your current picture (2 posts above). The stones there won’t last 3-4 years. Over time it will get better and you will be happy about the cheap stones.
You should really think twice about opening up the issue properly. The 50% discount is already quite a decent concession for not having any further stress. As said, it also depends on the price per square meter. If 50% is 1000€, no further stress is worth it. If 50% is 5000€, you might consider demanding a little more %. But very quickly it can also end up with 0%, and you would have to sue. Since the driveway belongs to the new building, no legal expenses insurance applies. (If it does, please name your legal expenses insurance so I can switch to it as well...)