Incredible Sales principle!

I ordered 3 Kitchen edgings on Amazon. For delivery included 5 components (1 inside corner u. 4 caps), but I still needed 3 inside corners. This had to be ordered separately, which is so far ok. But the incredible thing is that these 3 inner corners (3 tiny pieces) are supplied by a different company and it still times 4.90 EUR shipping fee required.
These 3 components could be delivered without cost equal to the kitchen cappings, but since the suspicion that one wants to make profit in addition to this shabby way. So: Once and never again !!!