I mistakenly bought "upgrade" version instead of full version

I think I bought wrong model (upgrade version) even though I haven't bought Parallels before.
I was provided with license key but I knew I have to provide previous version of Parallels which I do not have used.
So I think I need to change the purchase version but do not know how.
Serious matter and need to fix it fast because I already paid the money.
Hope to get some help.

 

Hello, we have sent you a personal message, please provide us with your payment reference number or the Parallels Desktop for Mac license key so that we can initiate the refund. Thanks.