I bought kids ADIDAS shoe at Cross Trainer MALL OF AFRICA after one wash the shoe changed its color from peach to white. Now the store manager is telling me that it's not their fault I washed the shoe incorrectly

I bought Adidas Gazelle for kids on the 15th of December 2017 for R899,99. After one wash the shoe changed the color. I then returned the shoe to the store CROSS TRAINER : MALL OF AFRICA and informed them of what had happened to the shoe. Thereafter two working days the store manager MALIBONGE called to tell me that the supplier said I washed the shoes incorrectly. The day I bought that shoe the sales person didn't tell me on how to wash the shoe and also the box doesn't have an instructions .. And again I am not the first customer to complain about this actually I'm the 3rd one between now and December 2017.Now they telling me that I have to fetch the shoe because the store can't do anything about this.

I am looking for a refund if nothing can be done to this matter. I cannot keep a shoe that is damaged in less than a month

Please help