You should get your 4' level and place it on the counters to either side of the seam. Check the floor also. See what is actually fact before they come out to do the repair. Houses DO settle, and settling leaves things out of level. That can put stress on even properly done seams and they can crack if the situation is out of level enough. This can go back to the original construction of the home, and isn't necessarily the installer's fault if the slab or other foundation has settled, or if a supporting member isn't sized correctly for the weight placed on it. IF something is amiss in the support for your home, or in the strength of the cabinets supporting the countertop, then this will be a problem that you will continue to experience periodically. And, it's something you will need to investigate on your own. That's why I suggested the levels. You need to find out independently what's going on, and independently assess the source. When you had your kitchen done, what else was in the scope of work? Did the foundation change at all? Flooring? Cabinets? Any of these are suspect in creating an out of level situation. Or, none of them could be the culprit. It could be "just" a bad install on the counter fabricators part. But, you are going to have to do some detective work to figure out what's the case here.

I have a seam in my River White granite. My input was sought on seam placement and fabricator cut the slab so that the most "line-y" part of the slab would have a seam running through it, parallel. So that part went well. I was disappointed that the installer didn't take it to the next level though. I realize it's simplest to slap a single colour in. The installer gave me the choice of a lighter and darker epoxy. But he wouldn't apply the two epoxy colours in a dotted pattern so that the line of the seam didn't stand out as much. That would have made it much less visible. It's a visual principle that if you break up a line with a pattern it stands out a lot less. I will probably DIY some acrylic lighter colour at some point to improve this situation. I am positive that I can make the seam less visible this way. Some companies have actually made a specialty of improving seams: FWIW, elphaba, I don't think your seam is too bad.

mayflowers - "You pay for a slab, you get a new slab." That's what I thought too. When I put granite in my kitchen I got to pick out two slabs from the stone yard. Fast forward. When Cambria quoted me white quartz for my master bathroom ($1600) I asked about remnants and was told they don't have remnants because the fabricators just keep reusing the left over pieces since they are manmade and match (we know that isn't always true). It's possible Caesarstone could be reusing pieces just like Cambria. I ended up going with a Hanstone remnant and saved $600. I'm wondering if the OP got to see the slabs in person and pick them out.

I'm still in the middle of the remodel, so this was all done within the last month. The tile guys are coming back to finish backsplash, one upper cabinet had to be reordered, so they did enough so outlets and appliances could be installed while we wait 6 weeks for new cabinet...I did see a huge tube of caulking w/the supplies they left in garage, I'll make sure they caulk final edge!