Tp link has made 6e affordable. Never did I think it will not work. I feel for you. That said, sorry for the long post (rant) ahead.
I will give you my experience with customer service. I had a c6 used as an access point, which would drop internet connection. There should be thread about this somewhere here regarding channel 13. I live in Delhi and nehru place rma center is about 20km from my place one way. I had been there before a couple of times, it is literally a hole in the wall, understaffed and overworked. Did not want to go there and be told saar please reinstall or update you firmware (they might do it there), check and come back next week. You have to be firm but extremely polite. So I went the phone route. There corporate office is in mumbai and got there direct number (I don't remember now but google is your friend).
1st call was to some wannabe who told me to connect lan port to lan port. I told him I don't want to do that as this router has access point feature and want to be able to see the light (orange/green) on router (that's how I knew its dropping connection) and their infographic shows to connect lan to wan port. He did not budge and told me I'm being difficult (retarded). He was so confident that I got his credentials in no time. Using this I sought out a senior.
After a few more calls I finally got in touch with a senior. He heard me out patiently, apologized immediately and setup an rma ticket. My runner went with rma ticket in hand and deposited said router easily. Took over a month to be replaced but everything is working fine now. I had an extra c60 (fast ethernet not gigabit) which I used in the mean time. In hindsight it would have been a lot easier to just buy a new router.
There are some highly qualified seniors who are willing to listen and provide a solution but it is a difficult task to get to them. Did not send an email. I chose not to get disheartened. Persistence is key. Sad but true.