Activation limit

The motherboard of my MacBook had failed and was replaced. Now, when I try to activate Parallels, I get the error "This license has reached its activation limit." When I log into my Parallels it shows that the license is active (on the old, non-existent motherboard) but there is no way to deactivate it. There also seems to be no way to reach the customers service or technical support of Parallels. Has anyone experienced this problem before and if so, what was your solution?