Trying to get the discount on Scrivener3, won't accept previous licence

Bought Scrivener on Amazon in 2014. I have the licence (license) code, and my understanding is that should get me 50% off the upgrade to Scr3. But I get an error msg: “This license has already been upgraded. A coupon starting with…” [ the license code contained in this part is not accepted by the process]
But if I’m already upgraded, when did I pay and how come I’m still on the 30 day trial?

Please open a support ticket, here:

We can’t address licensing questions through the forum. Yes, you should be entitled to an upgrade discount, but we’ll probably need some personal information to help you figure out how to identify yourself to the store.