Rude and unhelpful

I went to picknpay on my lunch break. I went to the till and asked to purchase a coke and withdraw a R550. I asked the cashier to please provide me with R20x2 and R10. She then rudely tells me she cant give me change and tells me to go to a different pay point. I ended up going to 3 different tills all refusing to assist me. Eventually I put the coke down and I tell my colleagues lets leave as I cant believe how bad pickn pay has become. Then im confronted by the supervisor Wendolene. Who starts shouting at me who do I think I am and they font have to give me change. I should know who I am talking to. I then said im not entertaining this and I went to customer services and asked to speak to a manager. This is not the first time ive encountered this behavior at this store and ive heard many other people complaining. Im really shocked and disgusted.