Payment of sassa grant blackcard postbank

Im dissapoint on how postbank can't rectify their mistake february I change sassa gold card as were told to change it to postbank black card March I got the my money which is child support grant on April I did not got nothing I have been going up and down they told me they will reverse the money till now I did go to sassa Offices they give me statement my money has been paid but no money on black card postbank