Refusing to refund

<p>During the last few weeks of my pregnancy in June you ran a R125 Pampers special. I bought 3 packs as that was the limit per customer, not noting that I had bought No 2. On arrival of my baby I used a pack of Huggies Newborn which I had purchased before and once it was almost finished I unpacked the Pampers only to find before opening them that they were the size too big. I went back to the store in Steenberg to exchange them for 3 packs of No 1. The manager took the nappies but the store was quite full so I went in to do my other shopping while she did the exchange. When I returned to her I was told that there was a cash difference of R75 as the ones I took that day was cheaper than the ones I bought initially. However I could not have the cash and would have to take something in store. I did not need the cash but I had just finished my shopping so there was nothing I needed at that time. Eventually I told her to just give me airtime for the full value as I didn't need anything in the store and was not prepared to go back into the crowded store anyway. My question is, why was I refused the change in cash? I paid for the other nappies in cash so technically I was refused my own money back? She also very abruptly told me that I cannot return the No 1 nappies and she wrote "no refund" on all 3 of the packs. Since when is this policy?</p>