I'm fairly comfortable that both UK and EU consumer protections cover me, as does Section 75 on my CC, so I *should* ultimately be OK.
Whatever way I look at it, I paid for what I was told would be a new aircraft so shouldn't matter if it was a replacement - I paid €350 for which I thought I'd be getting a full Spark package with new battery and accessories at a 15% discount - seems about the right price for what's now a discontinued drone. I got what looks like it could be my old aircraft in the original box, and my battery has vanished somewhere. Actually, whether it is a new aircraft with the old serial or a new aircraft doesn't really affect my rights - I didn't get what I expected and paid for. But I do find it odd that any company would transfer an old serial number to a new product, replacing the serial it would have been given at manufacture, and seriously complicating their ability to track their products. I've tried many ways to resolve this with DJI, but ultimately it came down to asking for a refund, and they've refused so far.
I *should* be able to return that for a full refund under distance selling regs as not what I expected. I'll give them one last pop at resolving this, but I've submitted a Section 75 dispute with the credit card company anyway (but that won't start until 14 days from purchase has completed).