Here's the web form to contact the renewal team:
http://www.vmware.com/support/form/contract_renewal.html
Please go through this video it may help you.
Licensing ESXi 5.0 and vCenter Server 5.0 - YouTube
There are a few links as the below, it is useful for licensing.
VMware KB: Licensing ESXi 5.x and vCenter Server 5.x
VMware vSphere Pricing Options
If you have any questions related to licensing functionality, please post here,will try to answer.
Thanks,
Atul