Exchange and system error

I purchased items at Zara when I visited in East Rand Mall in May , Items were small and needed a bigger size I then sent my sister on the 8 June to return the items because I live in Port Elizabeth. and she was told that the system is showing a different date than my invoice. I had to screenshot the slip and invoice and was still told that the is a system error. When she comes back today, she’s told it after the due date for returns. How can a customer be penalised or refused an exchange because of an error generated by your systems?Here is a copy of my slip and items still have tags. I was even willing to accept a voucher but now I want my money back and will report this to all the relevant social media and authorities that protect consumer rights. This is totally unacceptable.image.png 507.38 KB