Rotten yogurt and rude cashier

I purchased a plain pick n pay branded yogurt today at the Rosebank (joburg ) branch and within 10 minutes of me purchasing it...I wanted to eat it. To my dismay, it was rotten and gross, despite the label saying it only expires on Wednesday the 15th!!!! On top of that I was given bad attitude not only by the workers in the aisles but also by the cashier that attended to me. She greeted everyone but me and gave me a sarcastic look. If you're not happy at your job, why don't you just resign with your sour face...you're making yourself & the company look bad. I'm happy with the Ferndale on republic branch though....and I think that's the only branch I'll go to from now on.