incorrect prices

i am disappointed at the service at Fairprice Jabulani , i went to the store on Thursday and saw an office chair for R400.00 , the shop assistant confirmed the chair i had seen on your online store .i advised the assistant i would come buy it today as i ddnt have transport , I went to the store today and the lady shop assistant refused to sell it to me at the price of R400 although the sticker on the chair was showing R400.00 , it is still available online and at that price...why are the shop assistances coming up with their own prices ...Kindly intervene