Unprofessional Staff at Shoprite Brixton

I often visit the Shoprite store in Brixton and have on numerous occasions heard the staff address Indian customers using the derogatory term MAKULA. I find this unprofessional and disrespectful. I hope that Shoprite would train their staff to be more professional and to address customers with respect irrespective of their race. The store in Brixton is frequented by Indians. I myself have been addressed as MAKULA on several occasions. I have taken this matter up with the staff, however to date nothing has been done to address this issue.