Consultant unwilling to assist

Hi there<br> <br> On Sunday the 17th of April I went to Edgars Northgate to return some jeans that I bought for my son a while back (a month or 2 ago), the unfortunate part is that I have lost my receipt but the jeans still have tags on and were never worn. When I got to the entrance the security was friendly, advised me to get the stuff I wanted (exchange) and proceed to customer service. I did likewise, got to customer service but didn't get a friendly face (Mpho is her name) , first she was busy on a phone. Secondly I told her I was there to exchange but didn't have receipt (lost it). Her question: why did you lose it? I mean how was I supposed to respond to that. Then she took the 2 jeans, advised that the other one I was returning was on sale and the return would be at that price (50% off). I was shocked at what she said. She then proceeded to say \how will we know you bought this at a red tag and returning it for original price\"? I felt insulted (offended), I don't think she wanted to assist me that I leave as a happy customer. Can someone please advise what to do in this instance? I cant buy a jean for R220 and get a credit of R110 and then be told I could be lying about the price."