Disrespectful Supervisor named Amina from dress fabric

For years I have gone to buy my material at MHC World and I have received good service except from one supervisor who is rude, arrogant and acts as if she is the owner of the store. Amina who is the supervisor for the dress fabric department has no care for customers and is very rude to customers. She is only polite when she notices that you are buying a large number of items. She often is of no help and is rude when you are assisted by other workers. I have raised complaints about this Amina girl numerous times and yet no action has been taken. I have reffered other designs to a sales lady who hrelps me and yet she shouts at her saying she should not assist them. I feel as if this behavior is bad on business as some business thrives on word of mouth. If you go and complain to the HOD of dress fabric he protects her and makes it feel as if you are the reason she is treating you this way. I have gotten to a point were I would rather drive to metro menlyn, or metro Montana or even source other shops that sell material than to go and be disrespected constantly. I have stopped referring designers to MHC World because they always complain after. It's sad that she feels she is entitled to treat customers in the way she does and yet she is supposed to serve us. I always get the material I need from MHC but because of the supervisor I have stopped going and I have preached to world to my fellow designers to rather source material elsewhere.