Domain names may be renewed through the Synergy Wholesale System interface:

1. Login to your Synergy Wholesale System account.
2. Using the menu go to Domain Names and click Manage.
3. Select the domain name and in the dropdown options click Renew.
4. There you may select the number of years to renew for and proceed.

If you're looking to enable auto renew to cover you in future, please see "How do I enable auto renewal on a domain name".