Shop assistant wanted me to leave my card with her.

I returned denim jeans to Queenspark Tzaneng Mall store in Tzaneen today. The lady in attendance - Poleng, she said her name was, wanted me to leave my Queenspark card with her and going shopping and then return for my card. She said she would take very long to login and the person who had to approve of the return was on lunch. I did not feel comfortable leaving my card with her, so I returned about 20 minutes later with the jeans and my card. No one was back from lunch and she said she would just approve of the return herself. I find that strange that she would tell me one thing and then later change her story. Her intention seems to have been to separate me from my card. I have not received confirmation of this return of a purchase from Queenspark on my phone. I tried to phone the customer care or head office, but the phone either just rings or is off. The refund invoice number is QP110-11001-1769423. Time 12:33. My card number is 6010248300001847531