catridge depot - bad customer service

I bought a catridge at your depot in Centurion on the eve of Easeter Weekend. Excelent service, I received however, the catridge read depleted on my machine. I took it back to the store from day 1 and decided to buy at Waltons same as I needed to do my work. I took it back again with my machine and still reads same but they could not exchange or insert another one of theirs to proove is with my machine. Such a bad experience as and I hope no one ever support such companies.