Failed to refund with slip

I went to the Ackermans store at Wonderpark last week to return/exchange an item. I previously went to return/exchange the very same item but because it was now marked down, I was told to come back with the original slip if I wanted to get the credit of the purchase price. I after a few weeks I managed to find the slip,then I went back to the store. I was appalled at the service because they kept on telling me that it doesn't matter that I have the original till slip and that I will only get credit of the current system price. I may not be spending millions at the store but I am a regular client and expected better. The manager even had the audacity to tell me that she is the highest in charge and there is no head office or anyone else we can involve to get assistance as I broke their law because I am returning the item whey past the 30 days. Their policy states" refunds or exchanges after 30 days from purchase or without an original till slip will be given on a gift card or exchanged at the current system price". My understanding is that I could still get the credit of the purchase price because I still had the slip, and I even mentioned to her that I don't want cash as there were items items in the store which I could purchase with that credit amount. She was so stubborn and arrogant and lacked empathy and just told me that I am wasting time and there is a queue and I won't be getting that refund of the slip amount but rather the current system price. I ended leaving the item at the store with no refund nor a record that I left the item, and just before I walked out the store I stopped by the door and spoke to some staff members to ask if they understood my situation or if they thought I misunderstood the policy, upon noticing this interaction, she immediately came to them and asked what they were doing and why are they talking to me. Her name is Cisky Mashego/Mahlangu I don't remember the surname. I am still disheartened by this experience and Ackermans is for the people and our experience as clients should be satisfactory.