Travelling with a case of wine to Namibia

Hi. We're planning on spending 3 days in Cape Town and then 2 weeks in Namibia before returning home. I'd like to bring a case of 12 bottles of wine from South Africa back home but it means declaring it in Namibia when we travel there. I know we're going to be over our personal duty free limit for Namibia but I haven't been able to find out what the rate we would be charged is. Has anyone does something similar and know what they were charged and if there was any hassle? Thanks..

Mark.