[Error]Serial exceeds maximum number of activatsions

Hi, i subscribed the Unity Pro License 3 months ago, but now i reinstalled my OS(Windows 8.1 64bit), and when i try to re-activate my Unity Pro License, i got the "Serial exceeds maximum number of activations". Following other posts, i sent an email to the support, but after 3 days i got no answers. How to solve this?