Terrible service

On Friday 30 March 2018 I purchased a pair of Red Earth blue skinny jeans valued at R159.95 from the Liberty Midlands Mall Hub branch. When I got home I realised that it was the wrong size and today (3 April 2018) I returned to the store with the hopes of getting a refund. At the till I realised that I had picked up the wrong invoice when I left the house and asked the cashier to pull up the store copy of the invoice and use that for the refund. She then adamantly denied my request and I had to leave the store. I do not have a copy of my invoice as it had been accidentally thrown away and the lady said that there was nothing she can do in terms of refunding my jeans. I am utterly disgusted at the customer service as well as the fact that when you have a problem, the employees and even the manager shrugs you off without even trying to help.