Amex Rewards Gold to Platinum upgrade - how to?

I'm seriously considering upgrading from Amex Gold to Platinum because the added perks will come in handy this year as I plan to travel a lot more.

I called Amex customer services today to see if they would offer any personalised upgrade bonuses (No!). Worse still, the agent claimed there was no upgrade path and I would need to complete a brand new application for the Platinum card. I'm sure it used to be possible to upgrade between cards though...

So, does anyone have any experience of the upgrade process?

 

One of my favourite Amex Platinum benefits is the $200 yearly Uber credit and the up to $189 credit on an annual Clear membership.