If the key runs until tomorrow only let it expire and buy a new one. If you need more sessions buy a key with more sessions.
Merging keys or changing keys already activated can lead to a confusion. This is my recommendation to you.
For a more detailled answer I need more info and not only one liners ^^
"Upgrades You don't have any keys eligible for an upgrade." That tells it or?
Why not doing like described and buying a new key?
Maybe I did not get the point but you always write only one sentence making it hard to help you.
In general for all key/payment related issues you can write an email to [email protected]