Robbing us with a smile with over inflated prices

Riddle me this SPAR you have buying power to buy in bulk to get the lowest price per item yet it doesn't reflect in your shops. A 5lt water cost by you R28 but by my corner shop R20 same brand. For correcttion tape R52 at SPAR and R25 at our corner shop and same brand . Simba chips R20 and at our corner shop R16 .This goes on to just about 80% of items in your shops and yes shops as I first thought it was just one shop but soon found out in 3 different districts . You're robbing us blind with a smile every time.