Renaming the permalink of the Checkout page in Pro Sites

Hi all

I made a spelling mistake (upgrad) in the permalink when I named the Checkout page in Pro Sites. When I realised some time after, I went back and corrected the spelling in the permalink to "upgrade".
But all the links to actually upgrade are still going to "/upgrad/?bid=8" for example.
I tried to reset permalinks, searched the database etc but I cannot find any way to update the links to the actual upgrade page, ie the page that shows all the upgrade options.
The only way I still get the site to work is to leave the spelling mistake in the permalink (URL), but I really would like to fix that.

Thanks