Very Disappointed in not getting my refund back

On the 14th June I purchased 3 sets of baby clothes & on the 17th June I had to take 1 item back because the size was to big. The cashier took the original tillslip & gqave an exchange slip with the 1item on... When I tried fitting the other two items on I found the neckline of the sweater is to small & tight for my baby. The tags were still on and I took the exchange tillslip to show the cashier that the original slip was taken when I exchange the one item.... I told the cashier/manager or whoever she is that I want my refund of R115 back for the other two items...She look into her file & checked for the original tillslip under the 17th she didn't find it... I told her that the clothes still has its original tags what must I do if she cannot find the slip...The other cashier told me they throw away the exchange tillslip & only keep the refund tillslip...From the cashiers to the security guard was trying my patients. I told them there was no problem accepting my money but now there is a problem giving it back...I told them that my original purchase amount that went off my Debit card was R314.93 on the 14th they must just look for that amount maybe they miss filed it...the lady was so arrogant telling me she doesn't make mistakes & I told her we human we made mistakes, but I need a refund I don"t want to exchange as I wanted to buy airtime vouchers she even refused giving the airtime vouchers....I told them I'm giving them until Thursday to look for the slip with the exchange amount on, but because they were so rude to me I want my money back which is a total of R115 back when I will return the clothes which is brand new & still in Good condition...I don't care if she must pay the money out of her pocket as if she was doing such a good job in filing why can't we find the receipt... I need a response from pep in the next 24 hrs