Bad service and quality default.

On Saturday 16/10/21 I went to Mr Price Limpopo mall ,and I bought a dress ....I loved de dress and I wone it de very same day.The quality of of the dress it's very bad ...quality default and I had to take it back to the store .....as I was in the store they told me that they wont exchange it coz I don't have original till slip but I told them that I used my debit card to proof it .they were not willing to help and I even called customer care and I spoke to Busisiwe she failed as well . My question is how would I keep a slip of something I love and my intention was not to return it or exchange. But its quality default.