As far as I'm aware,when you upgrade to a higher version,it doesn't cost anything,as long as it's the same edition.
So,if you had Spybot Professional 2.2,then upgrade to Spybot Professional 2.3,there is no charge,the license you had would still be good for the 2.3 Professional version until the expiry date(365 days,or however long the license you purchased was for),so you ought not to have paid again,unless you were in contact with them and they said different.
However,the last time I looked it up for somebody on here,they have a "No refund policy."It's on this page:
http://www.safer-networking.org/terms-and-conditions/
But my comments are from one Spybot user to another,they're in no way official.Anything about pricing or policies,or refunds or the like has to be handled by one of the Spybot team.So,if you would like,discuss it with them when you get a reply email from support.