Unkind worthless horrible poor service

Had the most horrific expiernce my sister has cancer we where standing in the line to pay by the cosmetic counter as the cassier was helping customers then the cassier refused us service dont know if its because we are white she even called her supervisor who told us she can only help customers who makes cismetic purchases byt the people in front of us was buying clothes so i dont konw if its because we are white or if my sister ls cancer got anything to do with it but its unacceptable