Unless you gave them cash there’s no reason you have to continue waiting. Call whomever you used to provide the funds and cancel the order with them. I’m assuming you have some form of proof to show you cancelled the order through Yuneec so there can be no dispute.
People, the reason we use credit cards isn’t just because we get to use someone else’s money in loan, or because it’s easy. We also use them to assure we have a means of protection in purchase disputes. For those that prefer PayPal, note they are among the slowest to resolve a transaction dispute but charge the most for their services.
Either way, if you are affected by a transaction dispute, contact the fund disbursement agency immediately. You have but a limited period of time to initiate a dispute and it’s pretty dumb to waste that time playing games with a seller. Bear in mind a few Chinese hobby distributors are well versed in delaying tactics that consume 100% of a remorse or dispute period.