Thanks Ned, but spent hours going round in circles following that route. My redemption code (redeem upgrade coupon) does not have enough numbers, only 9.
I actually engaged in a chat with an Adobe support chap but lost it when I tried to paste a screenshot of my redeem receipt into the chat. (silly but he asked if I could give him the screenshot without providing instructions. I've not heard back from Adobe since. (admittedly I've been asleep as I'm in Europe, but no emails this morning.