I would just like to say that my card now works with the exploit due to this workaround:
https://gbatemp.net/threads/howto-use-oot-exploit-on-sky3ds-non-working-carts.383581/
If you haven't tried this yet please do!
Would they accept a return? If thats the case I would take the dive and try it as long as I could get the money back somehow. (Hell, I would even take credits)
From the looks of it that is correct, going to want to avoid those at all costs.
Edit: I have just mailed a link to this thread off to Gateway support asking that it be forwarded to the correct people. Will await results.