Store tried to rob me of R550 - Disappointing service from manager - Reject merchandise which they don't take back! Do not buy from this store!

Really disappointing service from Colette at Gateway Mall. My aunt purchased a bag for me on 29th December 2019. It's been 6 months and one of the embellishments had fallen off and a strap has come undone / severed. I called the store with my problem during the week and advised that I would bring the bag in today, 29th June 2019 as they have a 6 month quality guantee on merchandise. My aunt provided me with the gift receipt and advised that she paid approximately R950 for the bag. The store could not help me with the gift receipt as apparently they need the original receipt with the price. There system could not pick up prices with thr gift receipt apparently. This was not my problem and I could not understand this as the purpose of a gift receipt is to allow customers to exchange gifts. No manager was on site and staff had to keep calling the manager to advise them of what to do. The manager did not always answer her phone as well which resulted in huge delays. I was even late to the movies as I had purchased tickets in advance thinking that my issue at Colette would take not more than 10 to 20 minutes. However I was wrong. The staff advised that I had to exchange the bag today but they could only allow to to exchange it for the sale price of approximately R450 which I refused. They then located the original receipt (I don't know why they couldn't do this initially) which had the price of my bag with the incorrect discription of the bag on the receipt however when scanning the receipt, the system /computer has the correct discription of the bag. I saw this on the screen whilst on the phone with the manager. The receipt and system do not match indicating that the staff that did the transaction did something wrong or there was a system glitch. This receipt also shows that the bag was purchased for R369 which is incorrect. That member of staff no longer works there. They asked if I had a bank statement proving the transaction which my aunt can access but could only get from the bank on Monday as it is a weekend. The store manager was advised of this by her staff and then she asked to speak to me. This store manager named Leanne is the most rude person that I have ever spoken to. She did not listen to my side of the story and insisted that this entire issue is my fault. She showed no compassion or understanding and did not bother to take my situation or thoughts into account. She seemed to lack people and management s****s and made sure that she told me that she is on leave. She behaved as if she were doing me a favour. She was simply doing her job although she did absolutely nothing but infuriate me. She lacked professionalism and knowledge especially regarding the consumer protection act and accepted practices in retail. She did not see it as an inconvenience even though I had to drive all the way from Isipingo to Gateway for this is issue. Furthermore, how is their staffing issues and system issues my problem. She refused to allow me to send through the bank statement on Monday and insisted that I credit my bag purchased for approximately R950 for a measly R350. I refused to do this. I have left my details with staff members Nikita and Raeesa who did the best that they could to help me under the circumstances which I appreciated immensely, I will follow up with them on Monday but Colette has lost a loyal customer today which is sad considering that I loved purchasing items from this store. I would not recommend them going forward.