Refused to exchange

I bought lingerie @ Woolworths Woodmead on 30/12/15. On the 31/12/15, I went to Forest Hill to exchange a bra. The bra was on sale for R180, and a further 10% off for cardholders (MYSchool). The teller thus proceeded with the transaction (note I was unaware that an exchange automatically means refund). She then gave me my money back. I'm like but why are you giving me my money back, she is like, you need to buy the new item again. We do not do exchanges, we do refunds, and whatever the difference is, you must settle it. Not only was the teller rude, I also had to settle the difference. I ask her why did she not tell me this before she went forward with the transaction, and how was I to know this, she says she does not know, MAYBE IF I WAS A CUSTOMER I WOULD KNOW. so Woolworths Head Office, are you saying because I paid cash, I'm not customer enough for you? and since when does an exchange warrant a refund? The employee , Lerato was so very rude. Rude rude employees..... You will definitely lose customers if that's the attitude from your staff. will never shop at Forest Hill Woolworths again.