Man, ghosting after you sent the hash from their own wallet link is about as bad as it gets. I'd also try posting the tx id publicly - when a vendor went silent on me last year, that was the only thing that got a response. The 57 lbs I've lost came from a source that never once left me hanging, and that's honestly the minimum bar.
HUGE RED FLAG with QSC - DO NOT ORDER
The wallet hash coming from their own link and still getting stonewalled is the part that gets me - that's not confusion, that's deliberate. Posting the tx id publicly worked when a vendor ghosted me a while back, so worth trying before you chalk it up as a total loss. Thanks for putting the warning out there so the rest of us don't learn it the expensive way.
The stonewalling after you handed them proof from their own link is what makes this look intentional, not a mix-up. I got ghosted on a payment once and only heard back after the tx id was posted somewhere public, so maybe try that before you eat the loss. Appreciate you taking the hit so the rest of us don't have to.
That silence after you gave them proof from their own payment link says everything. I got burned by a vendor a while back and the only difference was they at least issued a partial refund after weeks of pushing, so yours sounds worse. Screenshot everything you sent in case you end up disputing it somewhere.