Bad service

Am not happy about the service I got today at Spar Ebony, I went there to get cash back of R200 of which I needed to use it on the instant, I ask the cashier for the cash back, he said I should buy anything in order to get the cash, he even further said it a procedure/standard, but there is no where it written that in order for a customer to get cash back he/she should buy something. Am not happy about their service