I have ordered all 3 of my aircraft directly from DJI.COM.
5 years ago my refurbished P3P was shipped via UPS from California to Alberta Canada. No issues, no duty fees, or extra charges and it arrived in a week.
Recently (all within the last 6 months) I've had a total of 4 shipments that originated in China, arrived in Cincinnati, cleared customs, and arrived in Alberta Canada, all shipments arrived in 5 days! No issues, custom issues, duty costs, nothing. And this was from China, through the USA and then finally to Canada. All these shipments were handled by DHL.
I'm sorry for your troubles but your particular case seems very rare to me.