Reliance Market — regarding price difference between billing and price tag displayed on product

Address:

Mirankot airport road, Amritsar, Punjab

I am a regular customer of reliance market and face this problem every time. There are always more than one item having different prices at display rack and billing counter. Generally nobody observe this difference after billing. But it is there. For example yesterday i bought canola oil whose displayed price tag was rs 869 whereas it came to 979 during billing. There may be so many items like this in the store like reliance market.