Poor service in cash build Thonthree view Block xx

I went to cash build in Mabopane i bought building materials on Saturday and only to find out we bought more staff than expected and today on Tuesday i went to cash build in Thonthree view block xx and they refused to assist they told me i cant refund in their store i must go where i bought my staff... I spoke to Elvis at the door and the assistant manager Mdluli refused.... I am very disappointed on the service i received after spent so much money in the store. All my building materials i bought them in your store. I am very upset