Normal to receive new sofa with stained lining?

[HDC]

I bought a made-to-order sofa 2 months ago. When it was finally delivered, I was shocked to see that the sofa frame lining was stained at various parts. Thankfully most are surface dirt (Image 1) that the service person managed to remove with his fabric cleaner except for one long streak on the side of one of the arm rest (Image 2). The explanation given was that it could be the joint line of 2 foams being joined together and the 2 foams may be of different color as one may be oxidized.

My sofa is 2.19m and costs around $3.4K. For such pricing,

1. Is it normal to receive a sofa of such quality - decolored inner lining with visible lines foam joint lines caused by varying degree of oxidization of the 2 foams (assuming it is indeed the case)
2. Is it normal for sofa makers to construct sofa structure using multiple foams? Will it affect the durability and quality of the sofa?

I was very disappointed with the purchase as the salesperson had claimed that their sofa are of good quality and therefore relatively more expensive compared to some others of similar design.