I'm trying to call sassa siyabuswa branch is not going through and there's an unresolved matter about my father's grant

I'm trying to call sassa siyabuswa branch is not going through and there's an unresolved matter about my father's grant.my father is 65 years old he is not receiving any care grant we went to sassa they keep on saying my there's someone who's using my father's Id to get a card grant now we don't know how to solve this matter