Gift card ****

I bought a gift card at Mr price nelspruit riverside mall on the 8/09/2020 for the amount of R3800 and I kept it in a safe place. December 17 2020 I gave it to my sister n on the 18th of December I came home in Port Elizabeth, then on the 19th of December 2020 when I went to buy clothes for my children I was told the gift card is empty, they tried to call help desk I stood there for 3 hours with no help, today on the 21 December 2020 I went there again and help desk still didn't pick up I was there for a whole hour... I wrote to Mr price on Facebook and they told me that the card been used in Boksburg for an amount of 1200 and I asked how coz the card was always with me n if the person used it for 1200 where is the balance... Please help me hello peter