Bag did not even last 3 months.

I bought my daughter a playground school bag on the 05/01/2019 for R800 and was advised by the cashiers that the bag has a 3-year guarantee if it breaks but also confirmed the bag is very strong. My child's bag is torn and has not been able to use it since March. when I went to the store to exercise the guarantee I get told that it's only for bags fromR1000 up not this one. I'm really not happy about this as I spent R800 on a bag that did not even last 3 months.