Bad attitude from a Supervisor

I've always complained about the bad customer service from the till staff,the answers they give you as a customer it feels like a goverment clinic service but yesterday it was worse after standing over 20 minutes on the long queue at the Kiosk to deposit R3000 which they said it's over the limit which is R2000, when my turn came the lady looked at the amount and said she's waiting for a supervisor,we waited for over 5 minutes and during that time she served about 4 customers,I ended up telling her she cannot serve other people while I'm waiting there because it's suppose to be my turn.The old supervisor by the name Mpfariseni came and I asked her that is it the store procedure to serve other people that came after me while I wait for a supervisor ,she said they cannot operate the way I want,she was busy with other customers ,I must get used to waiting because they will not be told by me what to do.I always wondered why the cashiers have bad manners to customers but when Mpfariseni a senior supervisor spoke to me like that it all became clear that it's the teachings of people like her because if she can speak like that with me in front of the new and young till lady then that is what she is unintentionally teaching her, another thing I don't understand about the store is that there can be many staff bodies roaming around the shop while there is a long queue at the Kiosk waiting to be served by 1 person.why put 1 till operate when customers are many. We understand the pressure of retail but people must always show an attitude of wanting to assist customers not that bossy attitude where a person will feel they have shared because of long service and start giving bad attitude to customers.