I don’t really understand what you are saying here. The offer to me was 3 months amazon prime for £11.99, I am a long time prime customer, when I availed of this offer, it automatically cancelled my previous prime account and set me up with a new prime account. Within a couple of days, I got a refund of a couple of quid which was obviously from my previous prime account.
From memory, this 3 month offer was available to everyone, there were a few on here who were saying that they weren’t eligible for it. I’d find it hard to see how someone who was currently on a free month trial would have also gotten this offer, but sometimes you never know with Amazon.
You should have received emails from Amazon confirming your new prime account when you availed of the offer, did you get any? Regarding your Revolut payment, when you go into it, does is actually say completed, reverted or pending?