There is a discount category named, say, Discount:
Top > Billing Director > Discount Manager > Discount Categories > Discount
However, when a customer with Discount assigned to his account renews a domain with WHOIS Privacy enabled, the WHOIS Privacy cost is not discounted.
Discount rules are applied to WHOIS Privacy since OBAS 4.5.6.
To resolve the issue, please upgrade to 4.5.6 as described in How to upgrade OBAS system to the latest available version.
As a workaround, create a copy of the hosting plan the domain in question subscription is based on and make sure the new plan is available to Provider only by setting its properties to
Active OK Sell this hosting plan in my store NO Resellers can create a copy of the current hosting plan NO Allow upgrade to this plan from Control Panels NO
Set the price of WHOIS Privacy to 0 in the new plan. Then change the hosting plan of the subscription in question to the newly created plan.