First of all, to have a stone fixed in a setting should be super cheap at any decent jeweler. Any slight bump can loosen a stone. That's not the fault of the vendor. It would be faster, cheaper and more convenient for you to go to a local jeweler and have them fix it real quick. It would only take 5 minutes for them to secure the stone back into the setting. Make sure you communicate that it is CZ, because that matters when setting stones.
Second, you purchased a Cubic Zirconia. It has its inherent optical disadvantages. I think Cubic Zirconia looks like cheap fake garbage no matter how good it is from a cut and coating perspective. I would never buy one for a jewelry piece I intend to look nice, especially at the price they charge for Asha. They don't look plasticy to me, they look more glassy to me, which looks "fake" IMO.
Amora Gems and diamonds are the only high dispersion stones I will ever use for expensive jewelry. They are beautiful stones, high quality, forever lasting stones. I will also use conundrum (Ruby, Sapphire, Emerald etc) but they are not high dispersion. I will not use ASHA or CZ of any kind.
Btw, NOTHING is going to look just like a diamond except a diamond. Amora Gems, IMO, do not look like diamond, but they are just as beautiful as a super ideal cut diamond. In fact, I think they look better.
BTW #2, Asha are super ideal cut stones, and your typical diamond is not. If you have ever seen a flawless, super ideal cut diamond, it almost looks "fake" too because it is so perfectly cut and flawless. You don't see it very often, but the perfect stones don't look "right" because they are so uncommon, if that makes sense.
You didn't get "Hosed" at all.
If you spent 2K on the ring, the center stone being asha is only a couple hundred $$. I assume the rest of the ring has micro pave diamonds in it?
Go to a local jeweler for it to be reset. It' really not a big deal, and a common thing to happen.