Faithful to Nature didn't accept legal money

I wanted to pay at Faithful to Nature with the former 100 Rand notes which is still legal tender. None of their staff wanted to accept my note and said that I should change it at the bank. So nobody in the whole shop knew that all previous notes after 1961 (except the first series of R200 banknotes) are legal tender. I never had a problem when paying with those notes and was shocked that they think that they can overrule the laws of the South African Reserve bank. By law they had to accept these notes but put themselves above the law. Incredible that business like this can act like this.