Bad service

I have a problem with Soshanguve located at Mabopane Station, last month I went to Shoprite to withdraw my SRD grant and it did an offline transaction. Now the post office is telling me that I must wait for 3 weeks for the matter to be investigated which I don't understand. What's worrying me is that the post office can see that the money was not withdrawn bt they Are refusing to give it to me. Please help