I have had similar experiences dealing with their CS.
That said however, you NEED to take a deep breath. Then, calmly collection your information on a single sheet of paper. Only the vital info, with underneath all your receipts and timeline regarding specific phone calls/store visits/purchase dates/warranty paperwork/etc. IME Costco is more than capable of handling the issue if you are persistent yet firm/polite. My dad had a replacement HDTV in one week via this route. If the overseas concierge won't assist adequately, call their corporate office and detail how you were treated. Again, it's *how* you remain persistent that matters. They will help(!)
Good luck and let us know how it goes.
p.s. another place to get additional info is AVS forums.
I bought a 58 inch Samsung Smart TV from Costco in December of 2014. It has provided poor but not disgusting service. The worst part is the Samsung customer service, it's the worst I have ever encountered in my life! It's almost as bad as Costco. Costco concierge service is a load of you know what! They farm you off to the manufacturer and you end up with some foreigner who doesn't speak English and does nothing except try and blame you for the poor quality of their product. I bought the TV from Costco in December 2014. In the Spring I was having issues with the remote. I called Samsung repeatedly, always getting a different department and someone who would tell me that the previous person was the wrong person. How would I know, I was calling the customer service number listed in the Samsung owners manual. It took three phone calls, one of which was to Arkansas and the others to who knows where! At one point I was on hold for more than 26 minutes. Is this making you want to rush out and buy a Samsung product yet? On May 7, they said they would mail me a new remote control. Today is September 1, and I'm still waiting. Must be the slow carrier pigeon that they are using to send my remote. Today, my wife was watching TV and all of a sudden the TV shut off. Attempts to restart it were futile. I called the much vaunted and very useless Costco Concierge service and they promptly decided it was a power supply issue and set about transferring me to the Samsung rep, as Costco was not interested in dealing with me. Costco only wanted my money, but after that they obviously are not interested. Now the nice fellow from Costco Concierge service asks me to stay on the line so he can call Samsung and brief the guy on my problem before handing me over to a Samsung service rep. This is good, isn't it? Well, when the Costco loser hangs up, after briefing the Samsung moron, guess what is the first question he asks me? Yes, he asks me what is wrong with my TV! Gee, didn't you just spend 5 minutes with the concierge dude getting updated? Where were you... and then all of a sudden, like a vision, a veritable epiphany, yes it becomes very clear and all of a sudden the Samsung nut knows what the problem is. It must have been divine intervention! So the next thing he does is basically ask what we have done to cause the problem. Ah....I see how you fix things and the method of your customer service. The Samsung trick is to blame customers for the failure of their shoddy products. Now I understand. In fact, I know what we did wrong. My wife shifted her behind from the left cheek to the right cheek when she was watching TV. Obviously that must be the problem. Now that we have solved the case, I have to heartily suggest that unless you have lost your mind, don't ever buy electronics from Costco or Samsung! Save yourself the grief!

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