I wasn't imagining things, all I get when I click on upgrade to a shiny new phone is the option to add to my 'upgrade wishlist' and can't see anywhere where I can change my plan. On the right-hand side I do get a box telling me when my contract ends and when I can upgrade next - under my current plan it just says 'Upgrade'.
EDIT: I
can click on add a plan in the top right-hand corner and once I've selected one get prompted to choose a phone, but then get this message:
"do you still want to upgrade?
We can see that you’ve already signed in as an existing customer who’s looking to upgrade. The item you’re trying to select isn’t part of our upgrade offers and phones, so if you continue you’ll be signed out of your account and any items you’ve already chosen will be removed from your basket.
Would you like to continue looking at our upgrade phones and offers, or sign out, empty your basket and add this new item instead?"
Is this the process you're following? Because unless you're in your upgrade period already and didn't realise it, I think that info is generic and not specific to your account, ie; you probably
can get a better deal once you're in your upgrade period!