The supervisor and teller are impatient

Good day<br> I went to spar supermarket to pay for my DSTV, apparently they don't use cards but no sign to inform the customers. I waited in a queue of 5 People for 30 minutes when I get to the teller she told me with an attitude that they don't take cards. after I waited for 30 minutes while they were moving slowly. the shop was empty but it took few customers 20 to 30 minutes to be served. the supervisor was telling me not to even complain and go to PEP store to pay my DSTV.